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74470"65945

October 1979
$2 50

kilobaud

MICROCOMPU

for business . . . education . . . FUN!

In This Issue — 35 Articles

Including:

Special Emphasis on 6800 Systems Six Articles

The World Power Systems Scam page 56

Exatron’s Stringy Floppy: a Mass Storage Alternative page 98

Ulysses in Computerland: in Quest of Business Systems page 128

Inexpensive Logic Analyzer page 1 72

Complete Table of Contents on page 5.

from PEfiGCM

One-Drive System:

$399. (40-track) & $675. (77-track)

Two-Drive System:

$795. (40-track drives) & $1350. (77-track drives)
Three-Drive System:

$1195. (40-track drives) & $2025. (77-track drives)
Requires Expansion Interface, Level II BASIC & 16K RAM

Low Cost Add-On Storage for Your TRS-80* .

In the Size You Want.

When you’re ready for add-on disk storage, we’re ready for you.
Ready with six mini-disk storage systems — 102K bytes to 591 K bytes of

additional on-line storage for your TRS-80*.

• Choose either 40-track TFD-100™ drives
or 77-track TFD-200™ drives.

• One-, two- and three-drive systems im-
mediately available.

• Systems include Percom PATCH PAK
#1™, on disk, at no extra charge. PATCH
PAK #1™ de-glitches and upgrades
TRSDOS* for 40- and 77-track operation.

• TFD-100™ drives accommodate “flippy
disks.” Store 205K bytes per mini-disk.

• Low prices. A single-drive TFD-100™
costs just $399. Price includes PATCH
PAK #1™ disk.

• Enclosures are finished in system-
compatible “Tandy-silver” enamel.

Whether you need a single, 40-
track TFD-100™ add-on or a three-drive
add-on with 77-track TFD-200™s, you
get more data storage for less money
from Percom.

Our TFD-100™ drive, for example,
lets you store 102.4K bytes of data on
one side of a disk — compared to 80K
bytes on a TRS-80* mini-disk drive —
and 1 02.4K bytes on the other side, too.
Something you can’t do with a TRS-80*
drive. That’s almost 205K bytes per
mini-disk.

And the TFD-200™ drives provide
197K bytes of on-line storage per drive

— 1 97K, 394K and 591 K bytes for one-,
two and three-drive systems.

PATCH PAK #1™, our upgrade
program for your TRSDOS*, not only
extends TRSDOS* to accommodate 40-
and 77-track drives, it enhances
TRSDOS* in other ways as well. PATCH
PAK #1™ is supplied with each drive
system at no additional charge.

The reason you get more for less
from Percom is simple. Peripherals are
not a sideline at Percom. Selling disk
systems and other peripherals is our
main business — the reason you get
more engineering, more reliability and
more back up support for less money.

In the Product Development Queue . . . a printer interface for using your TRS-80* with any
serial printer, and . . . the£/ecfr/c Crayon ™ to map your computer memory onto your color TV
screen — for games, animated shows, business displays, graphs, etc. Coming PDQ!

™ TFD-100, TFD-200. PATCH PAK and Electric Crayon are trademarks of PERCOM DATA COMPANY.

•TRS-80 and TRSDOS are trademarks of Tandy Corporation and Radio Shack which have no relationship to PERCOM DATA COMPANY.

I PERSDM I

PERCOM DATA COMPANY, INC.
211 N. KIRBY • GARLAND, TX. • 75042

To order add-on mini-disk storage for your TRS-80*,
or request additional literature, call Percom s toll-free
number: 1-800-527-1592. For detailed Technical infor-
mation call (214) 272-3421.

Orders may be paid by check or money order, or
charged to Visa or Master Charge credit accounts. Texas
residents must add 5% sales tax.

Percom peripherals for personal computing’

2. INTE3TEC DATA SYSTEMS

The Honor Graduate

There’s been a lot of talk lately
about intelligent terminals with
small systems capability. And, it’s
always the same. The systems
which make the grade in perfor-
mance usually flunk the test in
price. At least that was the case
until the SuperBrain graduated with
the highest PPR (Price/ Perfor-
mance Ratio) in the history of the
industry.

For less than $3,000*, SuperBrain
users get exceptional performance
for just a fraction of what they’d
expect to pay. Standard features in-
clude: two dual-density mini-flop-
pies with 320K bytes of disk storage,
64K of RAM to handle even the most
sophisticated programs, a CP/M
Disk Operating System with a high-
powered text editor, assembler and

‘Quantity one. Dealer inquiries invited.

debugger. And, with SuperBrain’s
S-100 bus adapter, you can even add
a 10 megabyte disk!

More than an intelligent terminal,
the SuperBrain outperforms many
other systems costing three to five
times as much. Endowed with a
hefty amount of available software
(BASIC, FORTRAN, COBOL), the
SuperBrain is ready to take on your
toughest assignment. You name it!
General Ledger, Accounts Receiv-
able, Payroll, Inventory or Word Pro-
cessing ... the SuperBrain handles
all of them with ease.

Your operators will praise the
SuperBrain's good looks. A full
ASCII keyboard with a numeric key-
pad and function keys. A non-glare,
dynamically focused, twelve inch
screen. All in an attractive desktop
unit weighing less than a standard

office typewriter. Sophisticated
users will acclaim SuperBrain’s twin
Z-80 processors which transfer data
to the screen at 38 kilobaud! Inter-
facing a printer or modem is no
problem using SuperBrain’s RS-
232C communications port. But best
of all, you won’t need a PhD in com-
puter repair to maintain the Super-
Brain. Its single board design makes
servicing a snap!

So don’t be fooled by all the fresh-
man students in the small systems
business. Insist on this year’s honor
graduate ... the SuperBrain.

S INTERTEC
DATA

= SYSTEMS.

2300 Broad River Road, Columbia, SC 29210
(803) 798-9100 TWX: 810-666-2115

Solve your personal energy crisis.
Let VisiCalc Power do the work.

Or say you're an engineer working on a design problem and are
wondering "What if that oscillation were damped by another 10
percent?" Or you're working on your family's expenses and
wonder "What will happen to our entertainment budget if the
heating bill goes up 15 percent this winter?" VisiCalc responds
instantly to show you all the consequences of any change.

Once you see VisiCalc in action, you'll think of many more
uses for its power. Ask your dealer for a demonstration and dis-
cover how VisiCalc can help you in your professional work and
personal life.

You might find that VisiCalc alone is reason enough to
own a personal computer.

VisiCalc is available now for Apple II computers, with
forother personal computers coming soon. The Apple
II version costs just $99.50 and requires a 32k disk system.
For the name and address of your nearest VisiCalc
dealer, call (408) 745-7841 or write to Personal
Software, Inc., Dept. K, 592 Weddell Dr.,
Sunnyvale, CA 94086. If your favorite
dealer doesn't already carry Personal
Software products, ask him to
give us a call.

TM— VisiCalc is a trademark of
Personal Software, Inc.
‘Apple is a registered trademark
of Apple Computer, Inc.

With a calculator, pencil and paper you can spend hours plan-
ning, projecting, writing, estimating, calculating, revising, erasing
and recalculating as you work toward a decision.

Or with VisiCalc and your Apple* II you can explore many
more options with a fraction of the time and effort you've spent
before.

VisiCalc is a new breed of problem-solving software. Unlike
prepackaged software that forces you into a computerized
straight jacket, VisiCalc adapts itself to any numerical problem
you have. You enter numbers, alphabetic titles and formu-
las on your keyboard. VisiCalc organizes and displays this
information on the screen. You don't have to spend your
time programming.

Your energy is better spent using the results than
gettirtg them.

Say you're a business manager and want to project
your annual sales. Using the calculator, pencil and
paper method, you'd lay out 12 months across a
sheet and fill in lines and columns of figures
on products, outlets, salespeople, etc. You'd
calculate by hand the subtotals and summary
figures. Then you'd start revising, erasing
and recalculating. With VisiCalc, you simply
fill in the same figures on an electronic
"sheet of paper" and let the computer do
the work.

Once your first projection is complete,
you're ready to use VisiCalc's unique,
powerful recalculation feature. It lets you
ask "What if?" examining new options and
planning for contingencies. "What if" sales
drop 20 percent in March? Just type in the
sales figure. VisiCalc instantly updates all
other figures affected by March sales.

kilobaud

MICROCOMPUTING™

contents* ocf. 79

30 The SWTP Computer System First of a two-part series on disks for SWTP. P. Shuman, P. Stark

40 PAIA 8700 Revisited Continuing coverage of the 8700. This time -making music. Rod Hallen
44 Inexpensive TRS-80 Printer Interface Small System Hardware s TRS-232. Sherman P. Wantz
46 Eyes for the AC-30 Mod to add monitoring features to the AC-30. Jerry Sorrels
48 Expanded TRS-80 Disk Operations First in a two-part series. Allan J. Domuret
56 Anatomy Of a Scam The World Power Systems scam and how it fell apart. Terry Kepner
60 |U Business Software Made Easy A business-software-writing primer. Ernie Brooner
64 KIMCTR Measures Capacitance An enhancement to KIMCTR (May 1979). Clement S. Pepper
72 More TRS-80 Horsepower Adding 16K of memory and “Level III” BASIC. Ronald W. Cowart
78 Probos V Build an inexpensive, effective logic probe. Steve Dominguez
82 PET’S Keyboard Grows Up Send your Munchkin-size keyboard to Oz. Robert W. Baker
84 Hurricane! Track hurricanes with this program. Bryce Segar

88 Video DMA Interface for SWTP Systems Add direct memory access. D. Holten, J. Boehme

94 Ultimate Consumer Computer This British-initiated system will be available in the U.S. Frank J. Derfler
98 The Exatron Stringy Floppy An alternative to cassettes (slow) and disks (expensive). Bill Harvey
102 Calendar Program What will the boys at the service station say? Steve Tabler

104 Four More Commands for SSB DOS Increase the BFD-68 repertoire. Terry Perdue
110 Arena Go into battle with your computer. Richard Price

116 File Directory Analysis for North Star DOS Organize your NS disk files. Edwin Milne

120 Report on the Centronics 779 Printer An “opinionated but accurate” evaluation. Glen A. Deibert

122 Beefing Up PET Get machine language and BASIC in your PET. Kendal T. Rogers

124 AMI’S EVK Series Part 1 of a three-part series on a 6800 alternative. David L. Tietz

128 Ulysses in Computerland Obstacles in setting up a business system. J. Craig McLanahan

132 Apple’s Documentation Strikes Again The Apple ll Programmer’s Aid ROM. Kenneth Miles

134 Caps Lock, Not Shift Lock Give your shift fingers a break. Dr. Michael R. Dunlavey

136 Hardware Random Number Generator Try a hardware approach. Ken Barker

138 Bit Rate Clocks for Your Serial Interface An alternative to all the UART applications. R. R. Derynck

150 Exploring the Inequality of Bus Buffers All buffer chips are not created equal. John R. Cameron

154 Elfish Ideas Speed up your Elf’s input-output. Glen A. Popiel

158 Load Programs the SIMPL Way Check out this author’s loader; you might use it too. Harold B. Combs
162 Pig Latin Is this the ultimate in program protection? Ken Klosson
166 Touch Handle with care! This icebreaker could be a jawbreaker. Adrian R. Thornton
170 Program Debugging Straighten out misbehaving programs. Bob Bosen

172 Hardware Testing in Suspended Animation Build an inexpensive logic analyzer. K. D. Tentarelli
176 Sweetening the Bytesaver Increase the Bytesaver’s usefulness with this mod. Steven K. Roberts

Publisher’s Remarks -6, Output from Instant Software, Inc. -8, Books -9,
PET-pourri-16, New Products-21, Letters-27, Classifieds -108, Contest! -108,
Dealer Directory- 109, Corrections — 109

Cover: This month’s cover shows the Exatron Stringy Floppy (ESF) in use as the mass-storage subsystem for the SWTP
microcomputer. The ESF fills the gap between th& standard cassette and the floppy disk. For less than the cost of the lat-
ter, the ESF provides comparable reliability and eliminates the aggravation of slow operating speeds and high error rates
of most cassette systems. For more information on the ESF see pages 15 and 98.

micro info

taj This symbol next to a title in
the table of contents indicates
that the article is a business-
application article.

Manuscripts

Contributions in the form of manu-
scripts with drawings and/or photo-
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can assume no responsibility for loss
or damage to any material. Please
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envelope with each submission. Pay-
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material will be made upon accep-
tance. All contributions should be di-
rected to the Microcomputing
editorial offices. “How to Write for
Microcomputing" guidelines are
available upon request.

Editorial Offices:

Pine Street

Peterborough NH 03458
Phone: 603-924-3873, 924-3874

Advertising Offices:

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Phone: 603-924-7138, 924-7139

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Phone: 603-924-7296

To subscribe, renew
or change an address:

Write to Microcomputing, Subscrip-
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ingdale NY 11737. For renewals and
changes of address, include the ad-
dress label from your most recent
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subscriptions, include your name and
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11737.

Subscription
problem or question:

Write to Microcomputing, Subscrip-
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ingdale NY 11737. Please include an
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Kilobaud Microcomputing (ISSN
0192-4575) is published monthly by
1001001, Inc., Pine St., Peterborough
NH 03458. Subscription rates in U.S.
are $18 for one year and $45 for three
years. In Canada: $20 for one year and
$51 for three years. In Europe, send
89, -DM in Euroscheck or send credit
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Microcomputing, PO Box 782815,
Sandton, South Africa 2146. Austra-
lia: For subscriptions write —
Katherine Thirkell, Sontron Instru-
ments, 17 Arawatta St., Carnegie, Vic.
3163 Australia. All other foreign sub-
scriptions are $23— one year only
(surface mail). Second-class postage
paid at Peterborough NH 03458 and at
additional mailing offices. Phone:
603-924-3873. Entire contents copy-
right 1979 by 1001001, Inc. No part of
this publication may be reprinted or
otherwise reproduced without written
permission from the publisher.

Microcomputing, October 1979 5

PUBLISHER’S REMARKS

Wayne Green

Like to Make $20,000
A Month?

Yes, I know: It sounds in-
teresting if the work isn’t too hard
and the hours not too long.

There is a need, I feel, for the
development of manufacturers’
representatives in the microcom-
puting industry. I was making
some calculations of what a rep
might be able to earn to see if the
field is attractive enough to bring
people into this business. The
figures look good.

Let’s say we divide the country
into about 20 areas. With about
1000 computer stores currently in
business, this would allocate about
50 stores per area. This is probably
all one rep could handle without
hiring assistants, since he is going
to have to get around to most of
these stores at least once a month.

What would the rep do? Well, if
we take as an example a rep for In-
stant Software, he would check
the display in a store, make sure it
is well placed, make sure it is well
stocked, that all the newest re-
leases are prominent, that our
posters are on display, that store
clerks know how to demonstrate
the new programs, answer any
questions on programs from
clerks, replace any troublesome
programs, report to the factory on
sales, on any problems, on good
vibes and anything else of value to
the factory.

As the library of programs in-
creases, a rep is going to have his
hands full keeping stores in stock
and keeping records of sales, mak-
ing sure the billing is correct and
that stores stay on time with pay-
ments. This isn’t much of a prob-
lem when there are only 100 pro-
grams, but Instant Software is
aiming at supporting a library of
several thousand business, scien-
tific, educational, game and home
programs. Every store will have a
program library, which will be a
large part of their business, prob-
ably accounting for much more
sales and profit than hardware.

But let’s say that our rep is han-
dling just 50 stores, that there are
only 500 programs so far released
(one year from now at the latest),
that the average retail price of the
programs is about $15 ($8 for
games, $15 for educational pro-
grams and $100 for business) and
that each store sells an average of
. . . how many? Two per month?

Three? Five? Ten? Let’s take two,
so we’ll be sure to be underesti-
mating in every way. I think there
will be more like 500 stores in each
area within a couple years. I’ll be
disappointed if Instant Software
does not have 1000 programs re-
leased by mid- 1980. But taking the
low-ball estimate of 500 programs,
two average per month per store,
we come up with retail sales per
store per month totaling $15,000.
Fifty stores will make $750,000 in
sales for the rep in his area. A rep
would thus get a 10 percent com-
mission on wholesale ... or about
$45,000 per month commissions.

If it turns out that there are
10,000 stores instead of 1000 sell-
ing computers, multiply the above
figure by 10. If we have twice or
three times the number of pro-
grams released, double or triple
that number. If I’m wrong and
sales are only one tenth of my
estimate that is still $4500 a month
in commissions per rep.

If I’m near right in my projec-
tions, we’re going to have a bunch
of millionaire reps.

Stores won’t be doing badly
either. At the low figure of
$15,000 sales per month, their
profit will run about $6000! A
library of 5000 programs would
bring in around $60,000 in profit
per month!

So how can one get into this
lucrative rep business? This is not
for the lazy. It means working
hard seven days a week for a long
time building up the business. It
means having a car so you can get
to all of the dealers . . . and even-
tually a van or even truck for

PK0TSJS
iktowationa^

delivering programs and promo-
tion materials. One should have a
familiarity with microcomputers,
with selling, with bookkeeping,
with software, plus the determina-
tion to succeed.

It will take some time to develop
a reputation and to build up com-
missions. Of the 50 stores in an
area, probably no more than five
or ten are already stocking Instant
Software ... the rest will have to
be sold. There will be resistance
. . . there always is to something
new, no matter how beneficial it
is. Some dealers won’t want to
carry software for the TRS-80 be-
cause they aren’t selling it. This
means you’ll have to show them
how this will bring more cus-
tomers into their store and permit
them to take advantage of the
rapidly growing and highly lucra-
tive market in accessories for the
TRS. It means showing the dealer
that most newcomers to com-
puting are coming in via their pur-
chase of a TRS or other small sys-
tem rather than as a hobbyist, as it
was a couple years ago.

But even with five dealers and
only 100 program packages and
with the average retail price at $8,
a rep can right now, without
growth, make nearly $500 per
month in commissions. Each extra
store brought on line should in-
crease the monthly commissions
by a minimum of $160.

If we add in the 2300 Radio
Shack associate stores and fran-
chise stores, all of which have the
freedom to deal directly with In-
stant Software through a rep firm,
we’re adding about 115 more

stores per rep area . . . right now.
Can you sell TRS programs to
Radio Shack stores? If you can’t,
then you sure should stay in some
other business. Better go get a
degree as an engineer and not have
to work again.

Paris Micro/Expo

Sybex’s micro show in Paris was
well attended, with some very
familiar names exhibiting. Here
are some more photos of people
and exhibits at the show.

Software Support Critical

Several of the smaller manufac-
turers of microcomputer systems
haven’t thought very far ahead
and as a result are not aware of the
importance of software to their
sales when the time comes that
other systems have a large supply
of inexpensive software.

Let’s exaggerate just a trifle to
get the concept. Let’s suppose that
a prospective microcomputer
customer has been lured into a
store and is looking over system A
vs system B. One has the support
of several thousand programs—
some right down his alley for
business, some just a help in his
business, plus some games, securi-
ty, data base, word processing,
etc., which look good. The other
system has no programs available
at all. The price on the two systems
is similar. Which do you think he
will buy?

Here is the Heath exhibit. Actually , the interest in
kits seemed to be less than expected, so the new
Heath line of assembled units will probably better
fit the European temperament. Europeans don't
seem to be interested to a high degree in the hobby
aspect of microcomputers, but rather in using them
for practical business and scientific applications.

One of the most crowded booths all through the
show was the Tandy booth. The TRS-80 is a best
seller in some parts of Europe, and just getting
started in others.

6 Microcomputing , October 1979

Actually, the prices of the two
systems will not be similar because
the software support of one sys-
tem will so increase its sales that
there will be substantial cost
reductions to pass along to the
customer . . . and to the dealer in
terms of higher profits. A dou-
bling of production in this field
seems to result in a dropping of
manufacturing costs of about 25
percent. This can mean a drop of
about four times that to the
customer.

Unfortunately for the systems
manufacturer who does not push
hard for software support, the
more software developed for an-
other system, the more will be
developed. It is self-generating.
And the more software there is,
the better all of it is going to be. In-
stant Software is getting much
more selective about the software
being accepted for publication.
With some dismay, we are already
seeing our rejects coming on the
market from smaller publishers,
and we know that disappointment
is ahead for the people who get

suckered into buying these pro-
grams, which are usually pub-
lished at a higher price than the
better programs ISI is publishing.

The growth of software publish-
ing has been held back to some
degree by the costs of lab hard-
ware. The more money that has to
be put into hardware, the less is
available for salaries and the peo-
ple needed to get the work done.
Manufacturers may eventually
recognize this and work out some
system for helping software
publishers with their work . . .
and with equipment.

Business Software

The development of top-notch
business software for microcom-
puters is, as I predicted, taking a
lot longer than games . . . and
for obvious reasons for anyone
who gives it any thought. It takes
a lot of time, experience and
genius to write really good busi-
ness programs; plus you have to

have both the hardware available
and the language and operating
system before you can get a good
start.

Much of the business software
now coming into Instant Soft-
ware for publication has been
developed by individual pro-
grammers for custom applica-
tions . . . often in conjunction
with a local Radio Shack store.
Some of these programs are in-
dicative of what we can expect in
the future — programs, for in-
stance, for specific hospital func-
tions, for working with blood
testing systems to speed up their
operation and print out the
results of hundreds of tests, to
work with patient monitoring
equipment to keep a record of
many factors and alert someone
if anything gets out of acceptable
parameters, to determine the
doses of certain medicines from
tests by other equipment.

We’ll be seeing this depth of
business software developing in
many fields. We’ve already some
surprisingly sophisticated real

Reinhard Nedela and Sherry were busy at the Kilo-
baud Microcomputing booth with subscriptions
and Instant Software sales.

Sybex did a brisk business in their books, some of
which have now been translated into German and
French.

Bob Jones of Interface Age had a booth too. The
airlines lost his luggage for a couple of days, mak-
ing the first part of the visit a bit hectic.

Though Harold Buchbinder, the publisher of Per-
sonal Computing was scheduled to talk, he never
showed up, and the PC booth was vacant.

klloboud

MICROCOM PUTING™

PlIBLISHER/EDITOR

Wayne Green

EXECUTIVE VICE PRESIDENT

Sherry Smythe

ASSISTANT PUBLISHER/EDITOR
Jeffrey D. DeTray
MANAGING EDITOR

John Barry

EDITORIAL ASSISTANTS

Dennis Brisson
Susan Gross

ADMINISTRATIVE ASSISTANT

Dotty Gibson

PRODUCTION DEPARTMENT
MANAGER:

Noel R. Self

STAFF:

Cathy Callahan
Robert Drew
James H. Gray II
Bruce Hedin
Carl Jackson
Ken Jackson
Dion Owens
Patrice Scribner
Robin M. Sloan
John W. White

TYPESETTING

Barbara J. Latti
Sandie Gunseth
Mary Kinzel
Holly Walsh

PHOTOGRAPHY

W. H. Heydolph
Tedd Cluff
Terrie Anderson

PROJECTS EDITOR

Jim Perry

ASSOCIATE EDITORS

Phil Feldman
Rod Hallen
Len Lindsay
Tom Rugg
Peter Stark
Sherm Wantz
Ken Widelitz

BOOKKEEPER
Knud E. M. Keller
MARKETING/CIRCULATION MGR.
Robert LaPointe
BULK SALES MGR.

Judy Waterman
ASST. CIRCULATION MGR.

Donna Taylor
ASST. MARKETING MGR.
Harold Stevens
CIRCULATION
Pauline Johnstone
COMPUTER PROGRAMMING
Richard Dykema
INSTANT SOFTWARE
MICRO LAB
William F. Gollan
Scott Spangenberg
Palmer T. Wolf
Stan Wszola

EUROPEAN MARKETING DIR.

Reinhard Nedela
AUSTRALIAN DISTRIBUTOR

Katherine Thirkell

ADVERTISING

Aline Coutu, Mgr.

Bill York
Marcia Stone
Nancy Ciampa
Gaye Halbig
Lori Mugford
Rita Rivard
Eve Anderson
Kevin Rushalko
Carol Symonowicz

Microcomputing, October 1979 7

estate packages, but they are
nothing to what we’ll have in a
year or two when most brokers
will not only have immediate in-
formation on their inventory, but
also data on all neighboring inven-
tories and a wide range of calcula-
tions possible on the myriad of
methods for financing real estate.
The forms will be done automati-
cally, along with all billing, title
search and legal aspects.

I had to laugh at the innocence
of one manufacturer who thinks
of microcomputer business soft-
ware as a “bad joke . . . written
by amateurs.” I hope he keeps his
non-micro business going ... he
may need it. Many of the pro-
grams we are seeing are being writ-
ten by old-time professional pro-
grammers, some with PhDs in
computer science. Being a PhD
doesn’t mean you are stupid and
don’t know where the money is,
and the big money for the free-
lance computerist lies in soft-
ware — business software right
now, then educational, and finally
all kinds. Computers can handle
just about any timesaving applica-
tion once the programs are avail-
able. I will again predict that the
eventual uses for our microcom-
puters will surprise all of us. The
surface is just being scratched and,
as new programs are developed,
the need for more will follow.

As a publisher, I can look for-
ward to word processing helping
prepare material for publication.
Computers can then be used to lay
out pages and set them ready for
printing, even to making the print-
ing plates directly. Editors can use
a computerized index to list pub-
lished material for fast referenc-
ing. Computerized soliciting of
bids for printing and paper will
provide efficiencies and cut costs.
Computerized mail will speed
material for publication from
remote writers and editors. Com-
puters can help with determining
the imposition of pages on a larger
press. Computers help work out
the best ratio of advertising to
editorial material, taking into con-
sideration the number and place-
ment of two-color ads, three-color
ads, four-color ads and editorial
material with color.

Then we need computers to take
care of daily orders from in-
dividuals for current and back
issues. Computers can also handle
orders from dealers and whole-
salers. Computers will speed up
shipping and billing, bookkeep-
ing, handling plastic money, keep-
ing an inventory record and sales
records of all transactions. These,
in turn, will provide reports for the
circulation people so they know
which ads are working best and
what covers sell better than others.

Add in the replies to various polls,
and you have more need for com-
puters to provide a better product
at a lower price.

The microcomputer will be able
to help every business to operate at
lower cost and with more efficien-
cy. Plus it will take a lot of the
drudgery out of the work by doing
most of the routine. I think we will
be seeing all of these programs
evolving for microcomputers, and
I’m hoping that Instant Software
will be the major distributor of
these programs ... all over the
world.

In May we opened up Europe
for software distribution. South
Africa should be next in Septem-
ber. Asia will be opened up in Oc-
tober. The more outlets for soft-
ware there are, the more royalties
for the programmers . . . and the
better programs we’ll have to help
sell systems. Will systems with
poor software support sell? I can’t
think of any reason they should.

New Apple!

Though I’ve seen no releases yet
from Apple, the stores are now
selling a new model, the Apple
II + . We’ll probably hear more
about the changes involved, but
the immediate difference has to do

with the BASIC ROM, which
comes built in.

The Apple II came with Integer
BASIC installed, and you had to
add Applesoft via a plug-in board
to get floating point numbers,
high-resolution routines and a
much more complete BASIC. The
Apple II -I- system has the Ap-
plesoft built in, and you have to
plug in an Integer BASIC card to
run your programs written in that
version ... or to speed up some
functions. Delivery is expected
soon on the Integer BASIC
boards.

The Instant Software Apple
programs — Golf (001 8A), Bowl-
ing (0040 A), Math I (0073A),
Math II (0098 A)— are mostly in
Applesoft. Trilogy (0040 A) and a
second run of Math I (0040A) are
in Integer BASIC. Apple owners
not having both languages should
be careful when buying packaged
programs and make sure they
match the ROM they’re using.

Ripped Off?

If you have a serious problem
with a microcomputer firm, send
them a letter with all the facts in
detail, plainly and simply, and
send a copy to me. Kilobaud
Microcomputing protects its read-
ers more than any other magazine.

OUTPUT FROM ISI

Sherry Smythe

The number of programs avail-
able for microcomputers is grow-
ing slowly; most of the new entries
still are games. Dealers are not en-
thusiastic about this. They prefer
to see business-oriented software
since these programs will not only
provide program sales, but also
will help to sell their systems.

Oddly enough, one of the best
business programs released
(Business Cycle Analysis, a power-
ful management tool) so far has
been for the TRS-80, and Radio
Shack stores are prohibited from
selling programs other than those
released from Ft. Worth. This
may be costing stores thousands of
computer sales and costing Radio
Shack into the millions. Mean-
while, computer stores are en-
joying the bonanza, and TRS-80
owners are forced to find their
neighborhood computer store to
get any serious support for their
system.

Many dealers have been reluc-

tant to stock programs for systems
other than those they are selling.
The dealers who are stocking pro-
grams for all systems are finding
that their program sales are sub-
stantially better as a result.
Perhaps 85 percent of the new-
comers to microcomputing these
days are entering via a TRS-80,
and stores with no TRS-80 prod-
ucts are effectively chasing away
their best sales prospects.

Prospects for business pro-
grams are better and better. About
half the programs now being sub-
mitted for publication by Instant
Software are business-oriented.
Oh, the umpteenth financing pro-
gram arrived long ago and aroused
as much interest as another ver-
sion of Hangman or Mastermind.
When you consider how many
business programs there are to be
written, you wonder at this rein-
venting of the wheel. Many pro-
grammers are now getting to-
gether with business friends and

developing program packages for
them for mass publication.

The crew at Instant Software
has been growing. The programs
are now all cataloged on a TRS-80
with a couple disks, as are the
associate editors and their spe-
cialties. There is more and more
work for associate editors as more
programs are being translated for
use on more systems and also into
foreign languages ... in addition
to the usual evaluations of newly
submitted programs.

Disks

Increasing numbers of pro-
grams are being submitted on
disks, which is fine with us. There
is little reason for a business, even
a small business, not to invest in at
least a dual-disk system. Without
that minimum of on-tap memory,
few significant programs can be

used. Should the day come when it
seems better to sell a program on a
disk, Instant Software will go that
route. In the meantime, most pro-
grams — even the disk-based pro-
grams — are easily transportable
via cassettes, and this saves some
money.

We’re geared up to check out
and produce programs based on
NEWDOS, which is getting very
good marks from users. Judging
from reader reports, it appears to
be superior to TRSDOS.

Educational Programs

Games are not needed. Pro-
grams already listed as available
are not badly needed. Educational
programs are very much in de-
mand. But look here— if you are
going to write a program to teach

(see OUTPUT, page 190)

8 Microcomputing, October 1979

BOOK REVIEWS

The Cheap Video Cookbook

Don Lancaster

Howard W. Sams & Co., Inc.
Indianapolis IN
1978, 256 pp., paperback

All of us at one time or another
have probably yearned for a video
terminal. Some of us were rich
enough to afford one, but the rest
of us had to be content to struggle
with our eight puny data LEDs un-
til the day came when we could af-
ford a good terminal for our own.
Well, that day has arrived. Don
Lancaster has come to our rescue
with his latest “cookbook,” The
Cheap Video Cookbook , which
explains in detail how you can de-
sign and build your own terminal
for less than $20!

The big secret behind cheap
video is that there is relatively little
hardware used— a handful of
gates and a character generator.
The key to the system is the micro-
processor. Utilizing several rou-
tines in conjunction with a video
interface, the microprocessor does
all the “housework” such as
generating the video and sync
signals. By changing your soft-
ware structure, you can change
your terminal’s characteristics. As
a result, you can have a very sim-
ple terminal or a very versatile one
with almost any feature you could
want. Features include: any dis-
play format from 1 x 16 to 24 x
80; various character fonts from 5
x 7 dot matrix to Old English; 256
X 256 black and white graphics;
96 x 128 color graphics; a host of
control features such as scrolling
and reversed video.

The important thing to notice is
that no matter how advanced a
terminal you want, the price you
pay for an extra option is not an-
other fancy IC, but rather another
portion of your memory. And you
don’t need much memory either;
IK will keep you busy for quite a
while.

While the video system de-
scribed in this book has a lot going
for it (low cost and versatility), it
also has a few disadvantages. The
most serious one, perhaps, is that
it will not readily work with many
CPUs. The CPU must meet cer-
tain demands if the video interface
is to function properly. One re-
quirement is that the microproces-
sor be able to advance the program
counter once every microsecond.
It must also have 16 always-pres-

ent and fully decoded address
lines. Some systems just cannot
meet these requirements without
additional hardware, which means
more $$$.

Since the video interface de-
scribed in the book was designed
for 6500- and 6800-based systems,
computers with such chips as the
F-8, SC/MP, 1802 and even the
8080 will require modification to
be compatible. Depending on the
system, these modifications could
be extensive and difficult. Not on-
ly that, but the software will have
to be translated as well. In short,
conversion to another CPU will
introduce new problems and take
your creative talents to solve.

Since the video system in this
book is based around the 650x
microprocessors, it is necessary
that you be familiar with the 6500
machines as well as the KIM-1.
The author recommends that prior
to this book you read the follow-
ing: The TV Typewriter Cook-
book (Sams 21313); An Intro-
duction to Microcomputers ,
Volumes I & II (Osborne 2001 and
3001, respectively); user’s manuals
for the 6500 and KIM-1; user’s
manuals for your system.

Obviously, The Cheap Video
Cookbook is not intended for the
beginning hobbyist.

The Cheap Video Cookbook
contains five chapters. Chapter 1
deals with the foundations of
cheap video, how it works, what it
can do and which CPU to use.
Two new and very important con-
cepts are also introduced: the Scan
Microinstruction and the Up-
stream Tap.

Chapter 2 shows how to design
the software for the cheap video
system. Here we discover how to
build programs for the scan micro-
instruction, alphanumeric dis-
plays, high-resolution graphics
and full-performance cursors.
Editors and graphics loaders are
also described in detail. Inci-
dentally, owners of KIM-1 sys-
tems will be able to use these pro-
grams right out of the book.

Chapter 3 involves the design of
the video interface. The circuit is
designed step-by-step from the in-
struction decoding PROMs to the
output circuitry. Finally, you are
shown how to interface the system
with a KIM-1 and how to add a
video input to an ordinary TV set.

Chapter 4 is like an instruction
booklet for the many electronic

kits produced these days. The first
part of this chapter discusses cir-
cuit theory and the construction of
Don Lancaster’s latest TVT, the
TVT 6-5/8. All components are
installed one by one, and each step
is checked off after completion.
There are also several excellent
full-size patterns for the PC
boards and solder mask. In addi-
tion, chapter 4 contains complete
construction details for four addi-
tional add-on modules that give
the TVT 6-5/8 extra features such
as graphics (black and white and
color) and lowercase alphanu-
merics. With the TVT 6-5/8 and
each module is a troubleshooting
guide to help isolate errors in con-
struction and programming. The
chapter winds down with informa-
tion concerning modifications and
part of a chess program utilizing
the color-graphics module.

The principles of transparency,
which allow the CPU to compute
data and run the video interface
simultaneously, are discussed in
chapter 5. Several methods are
shown along with the 6500 soft-
ware required to make them work.

Four appendices finish the
book. Appendix A is simply a list-
ing of the ASCII code, while ap-
pendix B is an octal-hex-decimal
conversion chart (rather handy!).
Appendix C contains the pin-outs
of several ICs used throughout the
circuits described in this book.
Appendix D repeats the PC board
patterns scattered in chapter 4.

Overall, the book appealed to
me. The material is presented in a
clear, easy-to-understand manner
(provided, of course, you have the
necessary background material
previously mentioned) and can be
mastered in a fairly short time. My
biggest complaint is that the soft-
ware and most of the hardware is
designed primarily for the 6500
series CPUs.

Although I believe that every
computer system can be adapted
to use cheap video techniques in
some way, I don’t recommend this
book to anyone who doesn’t own
a 6500 or 6800 microcomputer.
However, if you do own another
type of system and are sincerely in-
terested in a $20 video terminal,
and you are willing to put much
time and effort into it, then I sug-
gest you either borrow a copy or
read the First chapter in the book-
store before you purchase the
book. That way you can determine

if cheap video is for you without
unnecessarily investing money
that would have been better spent
on some more RAM or even an-
other book. If you opt for the lat-
ter method, I suggest you hide
behind a bookshelf to avoid evil
looks from the shopkeeper!

Steve Dominguez
Golden CO

Programming in PASCAL
Peter Grogono
Addison-Wesley, Inc.
1978, $10.95

If you’ve been wondering what
all the hoopla about PASCAL is
then this is the book for you. Since
you’ll probably be seeing a lot of
PASCAL anyway, what with the
Apple II, TRS-80 and other ver-
sions coming out, you may as well
buy the book now and save your-
self some time later.

You can probably already tell
that I like this book. As a matter
of fact, 1 can’t say enough good
things about it. If we’d had text-
books like this when I was in
school, we wouldn’t have needed
teachers. Grogono takes you by
the hand and leads you through
the very most fundamental con-
cepts of programming through the
most powerful features of
PASCAL. The text is liberally il-
lustrated with actual programs
and easy-to-understand syntax
diagrams (finally— easy-to-read
syntax diagrams!) that make
learning the language a snap.

Chapter 1, an introduction to
computer programming, includes
a discussion of what a program is
and a short introduction to
PASCAL to help you get your feet
wet. I have a strong feeling that
even a non-programmer can learn
to write PASCAL programs with
no help but this book. Chapter 1 is
part of the reason for this.

Chapters 2, 3 and 4 cover much
of the language. With these first
four chapters under your belt
you’ll be ready to try some pro-
grams of your own. The clarity of
the book and the well-chosen ex-
amples should make these about a
weekend’s worth of reading even
for a total beginner.

Chapter 5 covers some of the
functions PASCAL performs,

( see REVIEWS, page 14)

Microcomputing, October 1979 9

SMALL SYSTEMS JOURNAL

Introduction

Our objective in this issue is to give the reader brief descriptions of two systems included in
the OS-DMS grouping— General Ledger and Payroll— which have not yet been shown in our
previous articles. Several of the reports created by these systems will be shown in order
that the reader might better understand the purposes of the systems.

OS-DMS General Ledger System

In the normal office environment there is a need to keep track of how much business is
done by the firm. Whether the amounts earned are normal or not and whether the company
is making a profitable return on its investments are samples of questions constantly posed
about a business. The figures utilized to answer these questions are measurements of
money, and the process of working with these figures is called accounting. The most basic
accounting report used in the process of keeping track of a firm's activities is the general
ledger, and any specific series of operations designed to reveal the financial status of a firm
is called a general ledger system.

A general ledger system may be manual or automated. It may be very simple for a small
firm or extremely complex for a large corporation with multiple divisions or departments.
In all cases, however, the basic objectives of having a general ledger are the same: enable
management to know how the firm is faring financially as well as make decisions and
forecasts from an informed position.

The OS-DMS General Ledger System is designed to fit into this office environment in the
following manner.

Cash is earned or borrowed, spent or loaned, and in other ways comes and goes. This
cash flow should be carefully controlled. This Is the objective of the cash receipts and
disbursements portion of this system. All incoming and outgoing funds are entered in detail
on the computer through the console terminal in a clerical operation. The payer or payee
name, the date, a reference number of some type, a general ledger account number and the
dollar amount of each activity are put into the computer as the transactions take place. An
input journal of the events that take place in this operation is printed so that the person
overseeing the cash flow (the manager) may review the activities when the need arises.
Periodically, cash receipts journals and cash disbursements journals are printed in order to
have records of the cash activities of the firm. At the ends of accounting periods, totals
from each general ledger account affected by the cash flow from the period are posted to
the general ledger, and the cash books for that period are closed.

While cash transactions make up a large activity area in business, many accounting en-
tries do not include a movement of funds. Buildings and equipment must be depreciated.
Items are bought and sold for promises to pay. Taxes and other expenses are accrued
through a certain date. All these entries must appear in the company's books.

In this general ledger system, these types of transactions are entered separately from the
cash movements. The routine through which these entries are made prints the general |ou r -
nal, a normal accounting entry ledger. Through this general journal, records are maintained
as to what activity has gone on at what time.

The data entry is constant in both the cash and non-cash areas. The end of an accounting
period is a point at which the entries for one measurable time period — usually a month or a
year— are stopped so that their contents may be worked with, totaled, compared to other
like periods and evaluated. This is the closing of the books. Reports such as the general
ledger, the operating statement and the balance sheet are printed for middle and upper
management’s needs. Data is stored for historical reference and analysis. Management per-
sonnel now have reports concerning a standard time period in a common format with which
they may make decisions that affect the future of the firm.

This system produces ail the reports mentioned above. It also takes care of expansion or
restructure of the general ledger system. Protection of the data through disk backup Is an
integral part of this operation.

The OS-DMS general ledger is open-ended. Though this system is large, and in itself is
complete, it Is just a part of the needed product for most users. Through the use of the
various other modules and the nucleus utilities of OS-DMS. there is much that may be done
to expand its capabilities. Every user s needs are different, so this is a necessary state. It is
felt that the base provided here can support this expansion.

The first area we shall look at is the input function. This general ledger system has two
specific input routines— one to handle cash receipts and disbursements and the other to
work with all other types of entries. The main difference between the two is that the former
creates a detailed transaction file of all entries, whereas the latter posts directly to the
general ledger master file. Sample Input journals are as follows:

CASH RECEIPTS OR DISBURSEMENTS INPUT JOURNAL 01/26/79 9:25

PAYER/PAYEE DATE REF # ACCT # AMOUNT

STARTING NEW ACCOUNTING PERIOD.

SUBTOTAL: 0.00

ADD RECORDS
. . . CASH RECEIPTS . . .

JOHNSON BAKERY

01/03/79

203756

1020

250.00

SMITH LUMBER CO

01/05/79

33398

4010

1 59.96

APEX STORES INC

01/10/79

12205

1020

500.00

CONSOLIDATED TRUST

01/10/79

330856

4010

3579.55

JACKSON DRUGS

01/12/79

222556

1020

300.00

WLW CAFETERIA

01/15/79

330564

1020

325.50

CITY FINANCE CO

01/17/79

440322

4010

1399.50

SUBTOTAL: 6514.51

ADD RECORDS

. . . CASH DISBURSEMENTS .

FIRST NATIONAL BANK

01/10/79

44032

2015

1 15.00

WILLIAMS EQUIPMENT

01/12/79

22034

5010

304.79

ACME INSURANCE CO

01/15/79

33944

5250

157.00

OFFICE PAYROLL

01/15/79

22045

5410

3022.50

SUBTOTAL: 3599.29

• • . END RUN . . .

FIGURE 2. CASH RECEIPTS OR DISBURSEMENTS INPUT JOURNAL

GENERAL JOURNAL

1/23/79

9:46

DATE

ACCT

NAME/ DESCRIPTION

REF NUMBER

DEBITS

CREDITS

1/10/79

1030

JOHNSON EQUIPMENT

33085

2579.40

1/10/79

2010

ACCOUNTS PAYABLE

33085

2579.40

1/10/79

1040

HAYES OFFICE SUPS

33057

13.78

1/10/79

2010

ACCOUNTS PAYABLE

33057

13.78

1/13/79

1330

GLOVER SUPPLY CO

33058

308.00

1/13/79

2010

ACCOUNTS PAYABLE

33058

308.00

1/ 16/79

4010

ALLIED STORES

55098

4500.00

1/16/79

1020

ACCOUNTS RECEIV.

55098

4500.00

1/16/79

1020

55098 CORRECTION

55098-C

4500.00

1/16/79

4010

55098 CORRECTION

55098-C

4500.00

1/18/79

1030

ALLIED STORES

55098

4500.00

1/18/79

4010

SALES

55098

4500.00

OPERATING EXPENSES
SALES EXPENSES

SALES SALARIES

2053.69

1 1.21

19858.55

1 1.99

ADVERTISING

359.98

1.97

3476.18

2.10

TOTAL SALES EXPENSES

2413.67

13.18

23334.73

14.09

GENERAL EXPENSES

SALARIES

684.30

3.74

6615.50

4.00

RENT

152.55

.83

1476.21

.89

TELEPHONE

392.23

2.14

4070.63

2.46

TOTAL GENERAL EXPENSES

1229.08

6.71

12162.34

7.35

TOTAL OPERATING EXPENSES

3642.75

19.89

35497.07

21.44

NET PROFIT— LOSS

6635.29

36.23

18983.31

1 1.47

FIGURE 5. OPERATING STATEMENT

TOTALS: 16401.18 16401.18

NET: 0.00

FIGURE 3. INPUT GENERAL JOURNAL

Other reports necessary for the smooth operation of a general ledger system are the utility
reports. Included In this category are printouts such as a chart of accounts and a formatted
master file listing. In the OS-DMS system, these two reports appear as follows:

In addition to the printouts from these input runs, we should also look at the end-of-period
statements. The first of these is the balance sheet, and the standard OS-DMS format is as
follows:

BALANCE SHEET
FOR PERIOD ENDING 9/30/78

CURRENT ASSETS
CASH

ACCOUNTS RECEIVABLE
INVENTORY
PETTY CASH
TOTAL CURR ASSETS

ASSETS

8591.99

6572.76

4502.78

753.83

20421.36

FIXED ASSETS
LAND
BUILDINGS

DEPRECIATION— BUILDINGS
EQUIPMENT

DEPRECIATION— EQUIPMENT
TOTAL FIXED ASSETS

12301.38

51348.55

-9417.67

10753.20

-4301.75

60683.71

OTHER ASSETS
PREPAID DEPOSITS
TOTAL OTHER ASSETS

528.56

TOTAL ASSETS

81633.63

LIABILITIES
CURRENT LIABILITIES
ACCOUNTS PAYABLE
DIVIDENDS PAYABLE
INCOME TAX PAYABLE
INTEREST PAYABLE
INSURANCE PAYABLE
TOTAL CURR LIABILITIES

3419.82

4106.09

1821.69

532.43

378.66

10258.69

LONG-TERM LIABILITIES
LONG-TERM NOTE
TOTAL LONG-TERM LIABS

9721.45

OTHER LIABILITIES
PREPAID SERVICES
TOTAL OTHER LIABILITIES

2670.18

TOTAL LIABILITIES

22650.32

STOCKHOLDERS' EQUITY
COMMON STOCK
RETAINED EARNINGS
TOTAL STKHOLDERS’ EQUITY
TOT LIABILITIES EQUITY

40000.00

18983.31

58983.31

81633.63

FIGURE 4. BALANCE SHEET

Along with the balance sheet, the other primary end-of-period report is the operating state-
ment. often referred to as a profit and loss statement. The standard OS-DMS operating
statement has the following format:

OPERATING STATEMENT
FOR PERIOD ENDING 9/30/78

CURR

% CURR

YTD

% YTD

DESCRIPTION

AMOUNT

SLS

AMOUNT

SLS

REVENUES

SALES

18509.10

101.06

167705.43

101.29

SALES RETURNS

194.35

1.06

2142.56

1.29

NET SALES

18314.75

100.00

165562.87

100.00

COST OF SALES

BEGINNING INVENTORY

1508.30

8.24

2503.48

1.51

ADD: PURCHASES

10210.44

55.75

103750.54

62.67

DED: PURCH RETS ALLOWS

820.75

4.48

9331.25

5.64

TOTAL GOOD AVAIL

12539.49

68.47

1 15585.27

69.81

DEDUCT: ENDING INVENTORY

4502.78

24.59

4502.78

2.72

TOTAL COST OF SALES

8036.71

43.88

1 1 1082.49

67.09

GROSS PROFIT

10278.04

56.12

54480.38

32.91

CHART OF ACCOUNTS 9/30/78

—

.............

...

.....

—

ACCT #

DESCRIPTION

ASSETS

CURRENT ASSETS

TYPE RCD

DEBIT/CREDIT

1020

CASH

ASSET

DEBIT

1030

ACCOUNTS RECEIV

ASSET

DEBIT

1040

INVENTORY

ASSET

DEBIT

1050 PETTY CASH

TOTAL CURR ASSETS

FIXED ASSETS

ASSET

MINOR TOTAL

DEBIT

1510

LAND

ASSET

DEBIT

1520

BUILDINGS

ASSET

DEBIT

1530

DEPRE— BUILDINGS

ASSET

CREDIT

1540

EQUIPMENT

ASSET

DEBIT

1 550 DEPRE— EQUIPMENT

TOTAL FIXED ASSETS

OTHER ASSETS

ASSET

MINOR TOTAL

CREDIT

1810 PREPAID DEPOSITS

TOTAL OTHER ASSETS
TOTAL ASSETS

LIABILITIES
CURRENT LIABILITIES

ASSET

MINOR TOTAL
MAJOR TOTAL

DEBIT

2020

ACCOUNTS PAYABLE

LIABILITY

CREDIT

2030

DIVIDENDS PAYABLE

LIABILITY

CREDIT

2040

INCOME TAX PAY

LIABILITY

CREDIT

2050

INTEREST PAYABLE

LIABILITY

CREDIT

2060
FIGURE 6.

INSURANCE PAYABLE

PORTION OF CHART OF ACCOUNTS

LIABILITY

CREDIT

OS-DMS GENERAL LEDGER MASTER FILE LISTING 9/30/78

ACCT #

DESCRIPTION

PREV BAL

TRNSACTNS

1000

ASSETS

1010

CURRENT ASSETS

1020

CASH

6270.46

2321.53

1030

ACCOUNTS RECEIVABLE

7191.22

-618.46

1040

INVENTORY

2503.48

1508.30

1050

PETTY CASH

778.40

-24.57

1499

TOTAL CURR ASSETS

1500

FIXED ASSETS

1510

LAND

12301.38

0.00

1520

BUILDINGS

51348.55

0.00

1530

DEPRECIATION— BUILDINGS

-8692.23

-725.44

1540

EQUIPMENT

10753.20

0.00

1550

DEPRECIATION— EQUIPMENT

-3980.66

-321.09

1799

TOTAL FIXED ASSETS

1800

OTHER ASSETS

1810

PREPAID DEPOSITS

507.21

21.35

CURR BAL RCD TYPE

DEBIT/CREDIT

SOURCE

OPEN 1

OPEN 2

H (HEADER)
H (HEADER)

8591.99 A (ASSET)

CASH

6572.76 A (ASSET)

A/R

4502.78 A (ASSET)

INV

753.83 A (ASSET)

3 (MINOR TOT)
H (HEADER)

12301.38 A (ASSET)

51348.55 A (ASSET)

-9417.67 A (ASSET)

10753.20 A (ASSET)

-4301.75 A (ASSET)

3 (MINOR TOT)
H (HEADER)

528.56 A (ASSET) D MO

FIGURE 7. PART OF GENERAL LEDGER MASTER FILE LISTING

OHIO SCIENTIFIC 1333 S. Chillicothe Road • Aurora, Ohio 44202 • (216) 562-3101

if Reader Service— see page 227

Microcomputing, October 1979 1 1

In addition to the reports shown above, of course, there is some form of printed documen-
tation created by practically every operation performed within the system. This is designed
to assist the user in recording his actions, but even more, to allow him to see where he has
skipped an operation. In all cases, the objective of the system has been to assist the user in
the management of his firm and give him better control.

OS-DMS Personnel/Payroll System

Payroll is a normal part of any business that employs more than one person. In order to
comply with various laws, an employer must maintain records of each payroll run made for
the firm. In response to this need. Ohio Scientific has developed the Personnel/Payroll
System under OS-DMS.

The programs in this computerized system allow the operator to perform three basic per-
sonnel functions. The first is to compile and maintain an accurate employee data file, the
second is to generate reports from this data, and the third is to run payroll.

The various primary options available In this system are as follows:

PERSONNEL AND PAYROLL SYSTEM

(1) INSTRUCTIONS

(2) EMPLOYEE EARNINGS REPORT

(3) CHECK FILE REPORTS

(4) PAYROLL FOR ALL ACTIVE EMPLOYEES

(5) PAYROLL FOR INDIVIDUAL EMPLOYEES

(6) EDIT PAYROLL INFORMATION

(7) EDIT EMPLOYEE INFORMATION

(8) EDIT CHECK FILE INFORMATION

(9) SORT PAYROLL INFORMATION

( 1 0) SORT EMPLOYEE INFORMATION
(99) EXIT

FIGURE 8. PERSONNEL7PAYROLL MENU

From the menu above, the various options available to the operator may be described as
follows:

Option 1 presents to the operator a series of instructions as to how to run the system prop-
erly.

Options 2 through 5 are covered in detail following this explanation. Options 6 through 1 0
are file maintenance operations used to put new employees on the file, change the informa-
tion in their records when needed and sort their records in various sequences as the occa-
sions warrant. These runs, while not the producers of the end product, are used with
regularity to maintain the various files. Options 4 and 5 perform the same operations with
one primary difference: the payroll run for an individual does not update the computer files.
When an out-of-cycle check is run for an employee, then the editing programs should later
be used to enter the data into his records.

The sequence of operations for all payroll runs starts with the presentation to the operator
of the run options. These are shown on the monitor screen and set the pattern for the entire
run. Following this, the entries for the individual employees are made. The computer gets
these through a dialogue with the operator as shown below.

POSSIBLE DEDUCTIONS

1 FICA 2 FEDERAL INCOME TAX

3 STATE INCOME TAX 4 LOCAL TAX
5 INSURANCE 6 OTHER DEDUCTIONS

SELECT DEDUCTIONS

FICA

IS THIS DEDUCTION TO BE USED ?

FEDERAL INCOME TAX
IS THIS DEDUCTION TO BE USED ?

STATE INCOME TAX

IS THIS DEDUCTION TO BE USED ? N
LOCAL TAX

IS THIS DEDUCTION TO BE USED ? N
INSURANCE

IS THIS DEDUCTION TO BE USED ? N
OTHER DEDUCTIONS

IS THIS DEDUCTION TO BE USED ? Y
ENTER THE AMOUNT OF THE EMPLOYEE DEDUCTION ? 50.00
FIGURE 1 1 . EMPLOYEE DEDUCTION CHANGE

At the end of the run the totals for the entire payroll run are made. These are needed for
several reasons, most importantly to insure that the amount of money being paid out is
known and can be deposited in the payroll bank account to cover the checks being issued.

PAYROLL FOR 7/3/79

TODAYS DATE: 7/20/79

TOTAL NUMBER OF EMPLOYEES PAID 4
AVERAGE OVERTIME HOURS 1 .86

REGULAR PAY

1749.35

OVERTIME PAY

51 74

COMMISSIONS

0.00

OTHER PAY

0.00

FICA

1 10.40

FEDERAL

228.58

STATE

15.97

LOCAL

18.02

INSURANCE

37.50

OTHER DEDUC

0.00

TOTAL GROSS PAY

TOTAL DEDUCTIONS
TOTAL NET PAY

410.47

1390.62

FIGURE I 2. PAYROLL SUMMARY

EMPLOYEE NAME ALCORN ALAN
EMPLOYEE NUMBER 0

« NO COMMISSIONS »
REGULAR HOURS WORKED ? 80
OVERTIME HOURS WORKED ? 2. 3
OTHER PAY ? 1 23. I 1

FIGURE 9. EMPLOYEE HOURS ENTRY

WAGE EMPLOYEE

When all the entries have been made and the totals printed, the check stubs may be printed
for the employees. A variation of this run is to have the computer print the actual checks,
but since check designs vary significantly from company to company, the actual check
printing program is riot included as a part of the system.

For filing purposes, the payroll register is printed and is then available for historical use.

With the information now known, the calculations of the individual’s payroll figures are
made and the following display of the results is made on the monitor screen:

EMPLOYEE NAME: ALCORN ALAN
EMPLOYEE NUMBER :0

CHECK FILE REPORT FOR THE 7/3/79 PAYROLL

TODAY S DATE: 7/29/79

REGULAR PAY:
OVERTIME PAY:
COMMISSION:

OTHER PAY:
DEDUCTIONS
FICA

FEDERAL INCOME TAX
STATE INCOME TAX
LOCAL TAX
INS' 'RANCE

400 00
17.25
0.00
123.22

WAGE EMPLOYEE

33.13

79.51

6.01

5.40

7.50

GROSS DEDUCTIONS
NET PAY

131.55

408.92

IS THIS CORRECT ? N

( 1 ) EARNINGS CHANGE (COMPLETE CHANGE)

(2) DEDUCTION CHANGE

(3) SKIP THIS PERSON
? 2

FIGURE 10. EMPLOYEE PAYROLL CALCULATIONS VERIFICATION

If the employee deduction change is desired, the following series of questions and answers
takes place between the operator and the computer.

OHIO SCIENTIFIC

7/3/79

OHIO SCIENTIFIC

7/3/79

NAME: ALCORN ALAN

NAME: BEACHLY jERRY

REGULAR HRS.

73.75

REGULAR HRS.

80.00

OVERTIME HRS.

2.50

OVERTIME HRS.

.32

PAY RATE

5.00

PAY RATE

3.75

REGULAR PAY:

368.75

REGULAR PAY:

300.00

OVERTIME PAY:

18.75

OVERTIME PAY:

1.80

COMMISSIONS:

0.00

COMMISSIONS

0.00

OTHER PAY:

0.00

OTHER PAY:

0.00

GROSS PAY

387.50

GROSS PAY

301.80

DEDUCTIONS

FICA:

23.75

FICA:

18.50

FEDERAL:

48.33

FEDERAL:

32.90

STATE:

2.95

STATE:

2.05

LOCAL:

3.88

LOCAL:

3.02

INSURANCE:

7.50

INSURANCE:

0.00

MISC:

0.00

MISC:

0.00

TOTAL DEDUCTIONS
NET PAY

86.41

301.09

TOTAL DEDUCTIONS
NET PAY

56.47

245.33

12 Microcomputing, October 1979

OHIO SCIENTIFIC

7/3/79

NAME: CALOWAY JOHN

REGULAR HRS.

80.00

OVERTIME HRS.

0.00

PAY RATE

733.83

REGULAR PAY:

733.83

OVERTIME PAY:

0.00

COMMISSIONS:

0.00

OTHER PAY:

0.00

GROSS PAY 733.83

DEDUCTIONS

FICA:

44.98

FEDERAL:

87.90

STATE:

8.15

LOCAL:

7.34

INSURANCE:

22.50

MISC:

0.00

TOTAL DEDUCTIONS 1 70.87

NET PAY 562.96

FIGURE 13. CHECK STUBS

CHECK FILE REPORT FOR THE 7/3/79 PAYROLL TOOAYS DATE: 7/29/79 PAGE: I

NAME: ALCORN ALAN

REG HRS: 73.75

REG PAY:

368 75

FICA:

23.75

OVT HRS: 2.5

OVT PAY:

18.75

FEDERAL:

48.33

COM PAY:

STATE:

2.95

PAY RATE: 5

OTHER PAY:

LOCAL:

3.88

INSURANCE:

7.5

OTHER:

GROSS PAY:

387.50

GROSS DEDUC:

86.41

NET PAY: 30 1 .09

NAME: BEACHLY JERRY

REG PAY:

REG HRS: 80

300

FICA:

18.5

OVT HRS: 32

OVT PAY:

1.8

FEDERAL:

32.9

COM PAY:

STATE:

2.05

PAY RATE: 3.75

OTHER PAY:

LOCAL:

3.02

INSURANCE:

OTHER:

GROSS PAY:

301.80

GROSS DEDUC:

56.47

NET PAY: 245.33

NAMECALOWAY JOHN

REG HRS: 80

REG PAY:

733.83

FICA:

44.98

OVT HRS: 0

OVT PAY:

FEDERAL:

87.9

COM PAY:

STATE:

8 15

PAY RATE: 733.83

OTHER PAY:

LOCAL:

7.34

INSURANCE:

22.5

OTHER:

GROSS PAY:

733.83

GROSS DEDUC:

1 70.87

NET PAY: 562.96

NAME: SMITH SANDY

REG HRS: 77.06

REG PAY:

346.77

FICA:

23.17

OVT HRS: 4.62

OVT PAY:

31.19

FEDERAL:

5945

COM PAY:

STATE:

2.82

PAY RATE: 4.5

OTHER PAY:

LOCAL:

3.78

INSURANCE:

7.5

OTHER:

GROSS PAY:

377.96

GROSS DEDUC:

96.72

NET PAY: 281.24

FIGURE 1 4. PAYROLL REGISTER

Another format used for saving and filing the information is that used for the earnings and
deductions summaries. If there are few types of earnings and deductions, these two may be
combined as a single report.

PAYROLL SUMMARY FOR 7/3/79 TODAY S DATE: 7/29/79 PAGE: I

NAME

REG HRS

OVT HRS

PAY RATE

REG PAY

OVT PAY COM

OTHER

ALCORN ALAN

73.75

2.5

368.75

18.75

BEACHLY JERRY

.32

3.75

300

1.8

CALOWAY JOHN

733.83

SMITH SANDY

77.06

4.62

4.5

346.77

31.19

PAYROLL SUMMARY FOR 7/3/79

TODAY S DATE: 7/29/79

PAGE: 2

NAME

FICA

FEDERAL STATE

LOCAL

INSURANCE

OTHER

ALCORN ALAN

23.75

48.33

2.95

3.88

7.5

BEACHLY JERRY

18.5

32.9

2.05

3.02

CALOWAY JOHN

44.98

87.9

8.15

7.34

22.5

SMITH SANDY

23.17

59.45

2.82

3.78

7.5

FIGURE I 5. EARNINGS AND DEDUCTIONS SUMMARIES

When ends of reporting periods pass, various reports are required for numerous govern-
mental agencies as well as the firm's own needs. To provide the data necessary for the pro-
duction of these reports, the employee earnings record is often used. This report prints all
payroll information about a given employee or about all employees for whatever payroll or
group of payrolls Is specified at the start of the program. It is formatted as follows:

NAME: JOHN DOE

ADDRESS: I 234 SOUTH LAKE STREET
KENT. OH 44240
PHONE: 898- 1121

PERIOD

ENDING

REG

HRS

OVT

HRS

TOTAL

HRS

PAY

RATE

REG

PAY

OVT

PAY

1/2/79

57.00

0.00

57.00

0.00

456.00

0.00

1/16/79

87.75

0.00

87.75

8.00

702.00

0.00

1/30/79

73.00

0.00

73.00

8.00

584.00

0.00

2/13/79

82.00

0.00

82.00

8.00

656.00

0.00

2/27/79

86.50

0.00

86.50

8.00

692.00

0.00

3/13/79

88.50

0.00

88.50

8.00

708.00

0.00

3/27/79

70.00

0.00

70.00

8.00

560.00

0.00

4/ 1 0/79

76.50

0.00

76.50

8.00

612.00

0.00

4/24/79

85.00

0.00

85.00

8.00

680.00

0.00

5/8/79

83.50

0.00

83.50

8.00

668.00

0.00

5/22/79

86.50

0.00

86.50

8.00

692.00

0.00

6/5/79

129.25

0.00

129.25

8.00

1034.00

0.00

6/19/79

80.00

0.00

80.00

8.40

672.00

0.00

7/3/79

86.00

0.00

86.00

8.40

722.40

0.00

TOTALS FOR THE PERIOD

REG. HRS.: 1171 .50 REG. PAY: 9438.40

OVT HRS: 0.00 OVT. PAY: 0.00

COM. PAY: 0.00

OTHER PAY: 466.02

GROSS PAY: 9904.42

EMPLOYEE EARNING RECORD
SOCIAL SECURITY NUMBER: I I 1 - 1 2-2222

DATE HIRED: 1/4/74

DATE TERMINATED: MARITAL STATUS: SINGLE

OCCUPATION: ASSEMBLER ALLOWANCES: I

OTHER

PAY

GROSS

PAY

FICA

W.T.

FED

W.T.

STATE

W.T.

LOCAL

W.T.

OTHER

W.T.

GROSS

DEDUC

NET

PAY

0.00

456.00

27.59

70.35

3.82

4.56

0.00

106.32

349.68

1 14.54

816.54

50.05

181.65

12.19

8.17

0.00

252.06

564.48

0.00

584.00

35.80

102.97

6.38

5.84

0.00

150.99

433.01

59.29

7 i 5.29

43.85

143.05

9.56

7.15

7.50

211.11

504.18

0.00

692.00

42.42

134.70

8.98

6.92

7.50

200.52

491.48

107.81

815.81

50.01

176.46

12.17

8.16

7.50

254.30

561.51

0.00

560.00

34.33

96.08

5.90

5.60

0.00

141.91

418.09

0.00

612.00

37.52

1 10.70

6.98

6.12

7.50

168.82

443.18

89.18

769.18

47.15

160.60

10.91

7.69

7.50

233.85

535.33

0.00

668.00

40.95

127.50

8.38

6.68

7.50

191.01

476.99

14.71

706.71

43.32

139.37

9.35

7.07

7.50

206.61

500. 1 0

0.00

1034.00

63.38

255.70

12.90

10.34

7.50

349.82

684.18

80.49

752.49

46.13

154.93

10.49

7.52

7.50

226.57

525.92

0.00

722.40

44.28

144.70

9.74

7.22

7.50

213.44

508.96

FICA W.T. : 606.78

FEDERAL W.T.: 1998.76

STATE W.T.: 127.75

LOCAL W.T. : 99.04

OTHER W.T.: 75.00

GROSS DEDUCTIONS: 2907.33 NET PAY: 6997.09

FIGURE 1 6. EMPLOYEE EARNINGS RECORD

The next issue will conclude our series of articles on OS-DMS with a discussion of the new
Educational Testing System. Quotation/Estimation System and the enhanced Inventory
System including order entry, inventory explosion and forecasting.

OHIO SCIENTIFIC 1333 S. Chillicothe Road • Aurora, Ohio 44202 • (216)562-3101

Microcomputing, October 1979 13

REVIEWS

(from page 9)

such as CASE statement, scalars,
subranges and sets. Chapter 6 in-
troduces arrays and records; chap-
ter 7 presents files. Titled
“Dynamic Data Structures,”
chapter 8 covers pointers and
linked lists in one of the most lucid
treatments I’ve ever seen. Chapter
9 finishes up the language with the
GOTO statement and some dis-
cussion of dynamic memory allo-
cation.

As soon as you have some grasp
of the language, you can read
chapter 10, which covers program
design. This is handy for the be-
ginner who may not have any idea
at all how to go about developing,
testing and debugging a program.
For the non-programmer who
wants to learn how, this chapter
alone is worth the price of the
book. Appendix D, “Program
Standards,” should be read along
with this chapter for a good
understanding of what makes a
program a good or bad piece of
work.

A section of the book simply
titled “Further Reading,” with no
chapter or appendix number, is a
boon to somebody like me who
knew absolutely nothing about
PASCAL before he picked up this
book. This section contains a good
PASCAL bibliography along with
information on the PASCAL
Users’ Group. Used in conjunc-
tion with your local college
library, this section will easily take
care of your spare time for about a
month.

Appendices A and B cover, in
summary, the vocabulary and syn-
tax of PASCAL. The syntax ap-
pendix (B) contains all those
marvelous syntax diagrams that
are spread throughout the text.
I’ve copied mine and have them
pinned to the wall in front of my
desk for quick reference while I’m
still learning PASCAL. Appendix
C, the last of the appendices, can
be safely ignored unless you hap-
pen to be using the CDC imple-
mentation of PASCAL. It con-
tains a discussion of the peculiar-
ities of that implementation and is
rather interesting, but probably
not much use to most readers of
the book.

After raving about the book for
eight paragraphs I have to register
my one complaint. Virtually all
the examples in the early part of
the book are mathematical. So are
the exercises at the end of the
chapters. Despite being a com-

puter-science major, I feel that an
introductory book like this should
make no assumptions about the
reader’s background. A program-
ming text not directed toward em-
bryonic engineers will be welcome.
Maybe someday I’ll write my own.

William L. Colsher
Lisle IL

Computer Power for the
Small Business

Charles J. Sippl, Fred Dahl
Prentice-Hall, Inc.
Englewood Cliffs NJ
1979, $15.95

This book is full of words. Vir-
tually all of them are arranged into
grammatically correct sentences.
Virtually none of these sentences
can convey any useful information
to the intended reader, the small
businessman.

If we may begin with a sum-
mary, this is the worst “technical”
book I have ever seen. The writers
don’t understand the technology
they attempt to report on (in much
too much detail); they don’t un-
derstand the requirements for
business computing; and there is
no way that their intended reader,
the small-business “operator”
(their term), could get past the
flood of meaningless (to him)
technical detail to what little good
advice the book contains.

To support these contentions,
let’s look at the authors’ reporting
of computer technology. “A
12-inch rectangular CRT usually
displays 32 characters in 8 lines.”
(Emphasis mine.) Now, they are
supposed to be talking about
business computers, including
micros, but that description Fits
the crudest of TV games at best.
“Usually?”

“The standard floppy is 9 inch-
es square.” (The italics are theirs
this time, saving me the trouble!)
If floppies were nine inches on a
side they would loose one of their
Finest attributes: the ability to be
shoved into a “standard” File
folder in a “standard” file
cabinet. It makes me wonder if the
authors ever saw a floppy, or a
ruler.

While on the subject of flop-
pies, the writers warn the reader to
be on the lookout for “prefor-
matted” floppies, which they in-
sist means “hard-sectored.” (Just
the opposite is the case, of course.)
Their warning is ridiculous to
begin with, as they claim that pre-
formatting will force the user to
adapt his file size to that required
by the preformatting. File sizes

are, of course, under control of
the operating system, and are in-
variably quite flexible.

I am not trying to nitpick. I
want to make it plain that these are
only a couple of examples of the
abysmal lack of technical expertise
displayed by the authors— which
makes their poor attempts to ex-
plain technology to the naive
reader a real imposition on his
valuable time and a waste of his
$15.95. And they don’t know
when to quit, roaming far afield
from the subject of business com-
puters to discuss everything from
microphones to robots, in great
detail and with gross inaccuracy.

I never knew that those funny
little bar codes on packages in the
grocery store are what is known as
the “Universal Produce Code.”
Just try to stick one on a head of
lettuce!

Moving on to the subject of the
requirements for a business com-
puter, the picture caption on page
77 opens with the statement that
“RCA’s Cosmac VIP is certainly
applicable to business uses . . . .”
The photo shows a gentlemen la-
boriously keying in what appears
to be a multiple-page program
through the VIP’s tiny keypad.
Now, the VIP is a Fine little ma-
chine as far as it goes, and it can be
used as an introduction to micros;
as the basis on which to build a
hobby computer; or as a toy. But a
business computer it certainly is
not!

The writers just don’t seem to
know what computing or data
storage a business requires. Hence
their statement that “a year’s
worth of records can very likely be
contained on— at most— two flop-
pies.” Did they ever interview
anyone using a computer in busi-
ness? What research led to this as-
tounding conclusion? A year’s
worth of records for an entire
small business on two floppies? It
would seem to be a wonderful
dream. Maybe it was.

Similarly detached from reality
is the statement, in the context of
discussing the smallest ($2000) sys-
tems, that software costs “can be
as much as half the cost of the
hardware.” This statement ap-
pears to be based on a single exam-
ple of a system used to control an
air-conditioning system— not a
business computer as such. It is of-
fered to a reader contemplating
the purchase of a business com-
puter as advice on what to expect
his software to cost. At best it is a
gross underestimate.

It is in the Field of business soft-
ware that the prospective com-
puter user needs the most advice,

and the most accurate advice. Un-
fortunately, this book contains
almost none. The chapter on soft-
ware lists computer languages
without explaining their features
or intended uses. It ignores the
subject of application programs,
which is of paramount importance
to the business user.

In summary, the writers have
tried to cover an incredibly be-
wildering array of technical topics
in a book intended to be a guide to
selecting a business computer.
And they do cover these topics —
with an impenetrable rubble of un-
necessary definitions and technical
inaccuracies, preventing the busi-
nessman from Finding what little
good advice the book does con-
tain. But the silly advice over-
whelms the good ... for in-
stance, the suggestion that the
businessman should read such
publications as “Digital Design,”
which is exactly what its name im-
plies, a periodical for digital -de-
sign engineers.

One accurate statement that the
book does contain is that the book
itself (ignoring pictures) “could
easily be contained on a single
floppy diskette.” Perhaps the
book should be on a floppy. It
would make it easier to return it to
the seller. And it should be re-
turned, on the grounds that it is
not at all what it is advertised to
be: “a complete and practical
guide” to selecting and using a
business computer.

But save the return postage.
Don’t buy this book.

One final, ironic quote from
Sippl and Dahl: “Something is
missing in the business computer
market: knowledgeability.” They
provide a prime example of the
truth of that statement!

Ken Barbier
Borrego Springs CA

Logic — Home Study Course

Milton Howard Aronson
Measurement & Control
Pittsburgh PA
32 pages, Paperback, $3

If you are in any way mixed up
with computers or logic devices,
you probably should have this
course. The course is actually a
“home study” article reprinted
from the September-October 1970
issue of the trade magazine Medi-
cal Electronics and Data. It be-
gins by explaining what logic is
and what it does. Assuming no
particular background in either

(see REVIEWS, page 108)

1 4 Microcomputing, October 1979

ESFEfl Isiuslatiar

JIM MA YNARD WORKING ON SOFTWARE FOR THE SS-50 ESF

NOW HEAR THIS! Membership in the ESFOA is automatic when
you purchase an Exatron Stringy Floppy. One of the purposes of
this Newsletter is to tell you about some of the interesting and useful
projects which have been completed by ESFOA members. Jim May-
nard, an expert programmer and hardware designer, has spent many
many hours during the past year developing the SS-50 version of the
ESF. Jim accomplished this monumental task singlehandedly and
deserves a big round of applause from all SS-50 computer owners.
Jim has some other exciting projects nearing completion.

Many other major software and hardware projects are in the works
and will be reported on here in coming issues.

STRINGY FLOPPY FOR SWTP

This month the newsletter of
the Exatron Stringy Floppy
Owners Association (ESFOA for
short) addresses the SWTP ver-
sion. in keeping with the theme
of this issue.

If you haven’t taken a close
look at the front cover, do it
now. You can see that the Exa-
tron Stringy Floppy is capable
of earning a living at the office
as well as in the more traditional
role as “Keeper of the Games”.
This exciting new subsystem con-
sists of a controller and up to
two transports. Combining the
economy of tape with the speed
and reliability of the disk, Exa-
tron gives you another choice.

The CONTROLLER is a
complete system on a board,
comprising a synchronous serial
interface, a data encoder, a clock
recovery circuit, and the nec-
essary latches for peripheral
control. Also on board are
EPROMs containing the soft-
ware drivers. There are four
sockets for 2708s; three are used
for the basic system software.
The EPROMs occupy memory
addresses $C000-$CFFF in the
standard configuration. However
the controller is addressable to
any 4K block in memory, and
you can order custom EPROMs
in any block to fit your system.

UTILITIES firmware consists
of the low-level drivers and an
I/O package designed to reduce
monitor dependency. No calls to
a monitor are used: I/O is accom-
plished by direct manipulation
of a serial interface for the con-
sole, and a parallel interface for
the printer. The console I/O is
done through a vector which
may be changed after initializa-
tion. The board cold-start rou-
tine sets the vector at Port 2 if
there is nothing at Port 1. The
printer is set at Port 7. The
utilities program has many use-
ful subroutines which can be
used by other programs.

SYSTEMS SUBROUTINES
are also contained in the firm-
ware. The command TBAS will
load and execute TSC 6800
BASIC, the fastest BASIC runn-
ing on an 8-bit microcomputer.
The command MBAS will load
and execute Microsoft BASIC,

Secretary, Fred Waters

which has data file capability, as
well as compatibility with Micro-
soft BASICs on other machines.
EDIT loads the TSC Text Editor,
an excellent line- and content-
oriented editor with many local
and global commands. ASMB
runs the TSC Assembler, a fast
mnemonic assembler with object
code generation into memory or
into a Stringy Floppy.

Other system commands in-
clude HSAVE, HLOAD, NEW-
TAPE, and ASN. For a system
having one drive, no drive num-
ber is specified in the command.
If you have a two-drive system,
you specify the drive number if
the command addresses the drive
not designated as the system
drive. This designation can be
changed using the ASN com-
mand. NEWTAPE is the routine
for certifying new wafers. A
fourth EPROM socket with room
for another IK of memory is
available for system expansion.

The TRANSPORT uses state-
of-the-art digital and linear tech-
niques. It reads and writes
14,400 bits per second, or op-
tionally 7200 bits per second,
with a typical error rate of 1 in
100,000,000 bits. The transport
has an average life of over 3500
hours. It has controls for motor
on, fast forward, tape mark,
wafer present, write protect, and
write enable. Power is supplied
by the controller.

The WAFER is a high-impact
plastic case, about the size of a
business card, and 3/16 of an
inch thick, enclosing an endless
loop of tape. The tape is wound
somewhat like that in the famil-
iar 8-track cartridge. Wafers are
available with various lengths of
tape: 5, 10, 20, and 50 feet. The
average life of the wafer is 2500
passes.

PRICES

Cntrlr + Trnsprt

$250.00

Trnsprt only

$124.50

TSC 6800 BASIC

$39.95

Microsoft BASIC

$43.00

TSC Text Editor

$31.00

TSC Assembler

$33.00

Advanced Programmer'

Guide

$20.00

Ctrlr, 2 Trspts, Micrsft, & TSC
software $499.95

ESF FOR THE TRS-80

Have all of you TRS-80 own-
ers out there seen the first two
ESFOA Newsletters? In the
August and September issues of
Microcomputing? If you didn’t,
borrow a friend’s, or go see your
dealer, and read them -they de-
scribe the TRS-80 ESF. It’s
delivered assembled and tested
at the factory, and within sec-
onds of connecting it up you
are ready to go. If you have any
questions about it, or need more
information, or want to order
one, use our toll-free number.
See the ordering information in
the box below.

The ESF for the TRS-80 has
met with great success. It fills
an obvious need, and thousands
of the TRS-80 owners were, in
effect, looking for the ESF be-
fore they even knew of its
existence. Disks are still expen-
sive, and are needed when you
have to store millions in bytes,
but they are not what most
personal computer owners are
looking for. Audio cassette re-
corders and playback machines,
along with audio-style cassettes,
have their shortcomings, and
YOU don’t need to be told
about that. [You should see
some of our mail! Extracts from
some of the letters, with horror
stories and condemnation of
cassettes and recorders are ac-
tually unprintable!] So ESFs are
being shown by their owners
with pride to their local TRS-80

Users Groups, and the word has
spread.

You don’t find many sub-
systems of this quality with an
unconditional 30-day money-
back guarantee. And there are
none, we believe, with a one-year
full warranty. To quote from
the Users Manual, the specific
purpose of the 30-day money-
back guarantee is to ensure that
all ESF owners are satisfied ESF
owners.

HOW TO ORDER

All versions of the Exatron
Stringy Floppy are covered by
a 30-day moneyback guarantee
and a one-year full warranty. The
ESF is delivered from the factory
assembled and tested. Prices for
the SWTP version are given com-
plete in the text above. The TRS-
80 version is $249.50, which
includes Microsoft Level III
BASIC. Instant Software on ESF
wafers are available at the list
price. BUS-EX, the TRS-80 bus
extension, is $15 for the 2-
for-1 model, and $5 for each
added connector. Wafers at 5,
10, 20 and 50 feet are $2.50
each and $20 for 10. Shipping
and handling is $3.00 per order.
CA residents add tax. Order fast
by calling our toll-free number
below and giving your Visa or
MasterCharge number.

User’s Manual and informa-
tion package is available at no
charge. Shipping and handling
is $3.00.

If you have any questions about the product, about Exatron, or

HOT LINE

800-538-8559

ESFOA, please call the Hot Line. Address letters to ESFOA, 3557

Ryder St., Santa Clara, CA 95051.

Stringy Floppy is a trademark of Exatron Corporation ^E 48

WITHIN CALIFORNIA

(408) 737-7111

* Instant Software on ESF wafers are available at the regular HST price

iS Reader Service— see page 227

Microcomputing, October 1979 15

PEI-POURRI

Good news at last. Things are
looking up at Commodore, and
good news seems to be on the ho-
rizon. In my last PET-pourri I
was a bit hard on Commodore.
This was due to a lot of negative
comments from other users as
well as lack of information from
Commodore. Commodore is now
trying to remedy all that. Many
new people are being hired. Train-
ing programs for PET dealers
have now been started. With a
good training course, PET deal-
ers will now be able to help PET
users locally with specific infor-
mation and assistance. Final ver-
sions of the PET printer and
dual-floppy manuals are now be-
ing polished and should be avail-
able soon. I’ve seen preliminary
copies of these, and they are a
vast improvement over the pre-
liminary manuals.

Commodore has products that
I believe are far superior to the
others in the field. The problem is
learning how to unleash the hid-
den power in the PET, printer
and floppy. Full potential of the
PET is now beginning to be real-
ized. Both the PET printer and
floppy include microprocessors
as controllers. A complete PET
system (computer, printer, flop-
py) can handle very sophisticated
uses. In the future we should see
some comprehensive, serious soft-
ware available.

Some of this software is al-
ready being finalized. Commo-
dore has just signed a contract
with the author of a fantastic
word processor. I saw a prelimi-
nary version and was amazed. It
was easy to use and had features I
thought were only available on
dedicated word-processing sys-
tems. I should have a copy of it
within the week, so next month I
should be able to relate more
about it.

Commodore Disk

Commodore’s 2040 dual-disk
unit holds a great deal of poten-
tial. The reliability problems with
the earliest units have apparently
been remedied, and the disk oper-
ating system has been improved.
The trick is in learning to use the
system. The preliminary manual
that comes with the disks is not
too helpful. The final manual is
being completed now and should

help a lot. The 2040 disk utilizes
the PET’s IEEE port and comes
set up as device #8. The manual
shows how to change this if you
need to.

Presently, the 2040 disk works
only with the new PETs. Soon
Commodore will begin shipping
new ROMs for the old PETs;
then the 2040 disk will work with
the upgraded old PETs. You can
only write on the front side of
each diskette, which holds about
170K, but you can use the reverse
side of the diskette if you careful-
ly cut out a notch on the left side
similar to the notch on the right.
Beware, however, that even the
smallest particle allowed inside
may ruin the diskette.

A significant improvement has
been made in the Commodore
disk operating system. DOS 3.1 is
now included with every system.
It takes all the drudgery out of
operating the floppy. Take errors
as an example. In the program
mode, your program can have a
subroutine to check for errors.
The final manual lists routines
that do this. In the direct mode,
you only need to hit one key, >
(greater than), and the error mes-
sage is displayed on the PET
screen.

The new DOS also eliminates
the need to type OPEN and
PRINT# commands for accessing
the disks in direct mode. Now you
simply type > followed by what-
ever you normally would have
had to enclose in quotes in a
PRINT# statement. Loading a
program from disk is now easy.
Just type / (slash) followed by the
program name. DOS takes over
and does all the work for you, in-
cluding deciding which disk has
the program. If you begin with
the character t (up arrow) instead
of / the program automatically
will run once loaded. And re-
member, the PET can use pattern
matching for finding the pro-
gram. The program Backgammon
3.4 can be loaded and run with
the following direct command:
tB*.

The asterisk tells the PET to
load the first program that begins
with the characters preceding the
asterisk. In this case, PET would
load the first program beginning
with B. If another program, such
as Baseball 2.5, preceded Back-
gammon 3.4 on the disk you
could use: tBAC*. Once loaded
into memory the program will

automatically RUN.

Which Disk for Your PET?

Do you own several PETs, or
do you also have an Apple and a
TRS-80? If you answered no,
then the Nestar dual-drive full-
size floppy disk system is not for
you. The Nestar Cluster One is
ideal for schools. Up to 15 PETs,
TRS-80s and Apples can hook up
to one Cluster One. Contact
Nestar (810 Garland Dr., Palo
Alto CA 94303) for the name, ad-
dress and phone number of your
nearest Nestar dealers.

Computhink Disk and News

Most readers probably only
have one PET. Two available
disk systems, which I have seen
work, are worth your considera-
tion. One, of course, is the Com-
modore disk. The other is from
Computhink (3260 Alpine Rd.,
Menlo Park CA 94025). Compu-
think’s disk system has been out
for over a year already. Readers
in the East and Midwest should
contact New England Electronics
(NEECO), 679 Highland Ave.,
Needham MA 02194, the Com-
puthink distributor for that sec-
tion of the country. NEECO now
has a new disk operating system
as well as a dual-density option.
Both sides of each diskette may
be written on, unless the disk pro-
tect notch is covered, then the
diskette cannot be written on.
With dual density, each diskette
can hold about 200K. Presently,
the Computhink disk will only
work with the old PETs; soon, it
should be available for the new
PETs as well.

The Computhink disk system is
designed to be plugged into Com-
puthink’s Expandamem. It uti-
lizes the PET memory expansion
port rather than the IEEE port.
The system comes with a diskette
containing utilities on one side
and helpful examples of disk pro-
gramming on the other. The utili-
ties include: Monitor, Datafile,
Diskcopy (to copy a complete
diskette from one drive to the
other), Random-Format (sets up
a direct -access file), DensityCopy
(allows a dual-density drive to read
a single-density diskette and

create a dual-density copy of it)
and two memory tests, PageTest
and BlockTest. The examples on
the other side are very helpful in
showing how to use the com-
mands explained in the manual.

Currently, Computhink is ship-
ping dual-density, dual miniflop-
py drive systems for the PET. By
early fall 1979, they should be
shipping this configuration with
an added bonus: You can read
both sides of each diskette with-
out having to take it out and flip
it over, thus having four sides of
dual -density diskettes on line — or
800K on line.

Computhink offers more than
hardware. They also have a PL/M
compiler available for their disk
system. A BASIC and FORTRAN
compiler will be available soon.
Also available now is a compre-
hensive data base. Contact Com-
puthink for details on these.

Computhink Disk Notes

In the short time that I’ve had
the Computhink dual-density disk
system I’ve developed a Menu
program, written for the new
DOS, that will enable you to load
and run any program on either
drive by hitting only one key. The
program first puts a directory on
the screen. Then an index-key
character is printed in front of
each entry. The program checks
which key is hit and goes to the
correct location on the screen. It
PEEKs at what name is there and
assigns it to F$. It then loads and
runs F$ from drive D. The pro-
gram keeps track of which drive
the directory came from and al-
lows you to hit one key to see the
directory from the other drive. If
you modify each of your pro-
grams to end by loading Menu,
you can have a continual chain
taking almost all the work out of
running programs.

I’m not a professional pro-
grammer. My program is a bit
long and can be written in a more
condensed form, but the program
now includes many remarks and
will be helpful in developing your
own version.

Disk Software

Business Software is available
for the Computhink disk from

16 Microcomputing, October 1979

gSSw'^ass?®^

Syste™

04sKOP^ tin9 6, tleOri

ONLV

sUB

HARDWARE FOR TRS-80 a

□ Pertec Disk Drives FD-200 $375.00 ea.

These are 40-track Drives that are completely compatible
with the TRS-8(rand Radio Shack Drives. 3.0 DOS included.

Will allow Turning Diskette over and Write on other side.

□ 4-Drive Cable for Pertec Drives $35.00

□ DECwriter III, 132 Character $2500.00

110 to 9600 band EIA tractor feed keyboard printer. This
is truly the nicest printer available. (30 day delivery)

□ 701 Centronics TRACTOR FEED

Bidirectional Printer $1 500.00

2 Vi times as fast as the Radio Shack 779 Printer, has full
size 132 Char. Carriage Bell tone. Complete with Cable
plug in and use. Shipped Freight COD.

□ 200 ns 16K Dynamic Memory Clips for Keyboard or Expan-

sion Interface, Lifetime Guarantee, complete $110.00

Lifetime Guarantee. Complete with Instructions and Jumper
Blocks.

□ 10 Key Numerical Keypad Kit $79.95

□TRS-80® Level II - 1 6k $750.00

□ Expansion Interface $275.00

□ RS-232 C Interface $ 89.00

ORDER NOW AND SAVE

Just list the items you want
and mail this convenient coupon.

USER OEE^ED ^ sE D«V|* . us£R DEVICE ^tgCg-^lONS

SOFTWARE BY ACS

□ Monitor No. 3 $29.95

Complete Machine Language Monitor for TRS-8ufeatures:
Find, EDIT, Relocate, Symbolic Dump to Tape, etc.

□ Monitor No. 4 $49.95

All of the commands that reside in Monitor No. 3, plus:
RS-232 I/O, Disk Program I/O, Symbolic Dump to Disk for
Loading into Disk Editor/ASM., Track & Sec I/O for
modification.

□ PCLEND $15.95

Will Patch ASCII files of Basic Programs or text or DATA
FILES so that they may be loaded into the Disk Version of
the Electric Pencil for Editing purposes comes on Cassette
that will automatically create a Disk file of PCLEND.

□ MAKE TAPE AND MAKE DISK

for Cassette Dealers $69.95

These are two programs that will allow you to take any type
of Program from Disk and store it on tape for mailing
purposes. When the user receives the program in the mail
on cassette, it is loaded into the computer which will
automatically make a Disk file of the program.

□CP/M & C BASIC for the TRS-80®

CP/M Includes: MOVCPM, STAT, PIP, Dump, DDT, ASM
(8080), ED, plus 6 user manuals.

CP/M $150.00

C Basic-2 Includes: XREF2, CBAS2, and manuals.

C BASIC 2 $99.95

□ G2 LEVEL III BASIC for TRS-80®. Special $39.95

□ TELCOM - Telecommunications for the TRS-80®. $29.95

Telecommunications for the TRS-8(f®allows one TRS-80®
to communicate with another through the RS-232-C over
the phone line.

Orders received by 6:00 p.m. shipped

next day on Master Charge, Visa,

^ Certified Check or Money Order.

Personal Checks require 14 days to
: ^WKj clear. No C.O.D. Collect calls not
accepted. All Hardware warranted for 90 days
except Radio Shack equipment which is warrant-
ed through Radio Shack. Software guaranteed
for replacement only. Prices subject to change
without notice.

Send Check or Money Order payable to —

SOFTWARE * P.O. Box 60097

Nashville, TN 37206

Quan. Description

Unit Price Total

v* A75

Automated
Computer
Software service

(615) 244-2798

Division of

♦ !*i ii|iii!i Hull

625 Main Street • Nashville, TN 37206

HANDLING CHARGE $1.50

TENN. RES. ADD 6% SALES TAX TOTAL

□ Check

□ Money Order

□ MasterCharge

□ Visa

Card No.

Exp. Date-

Name

NC.

Address
City _

State

Zip-

0 REM THIS IS MENU FOR DISK

1 REM IT HANDLES UP TO 3? FILES

2 REM IT HANDLES ALL CHARACTERS IN

3 REM NAMES EVEN SIMPLE REVERSE

4 REM FIELD IF THE REVERSE FIELD

5 REM IS TURNED OFF U1THIN THE NAME

6 REM

7 REM

10 INPUT "CCLRK 2 DOUNK 2 RIGHT3UHICH DRIVE* 1C 3 LEFTI“;D
20 POKE 525,1 :POKE 527,9?

30 tD,D

100 PRINT "CHOMEISiSHIT THE CRVSIKEYCOFF] OF YOUR PROGRAM CHOICEiSS"

110 PRINT "CUPimHIT [RVSmOFFHLEFTHDOUNrCUPI TO STOP - HIT [RVS3MOFFKDOUNKLEFT3KUP3 FOR DRI

190 M=3?B88:REM FIRST INDEX LOCATION

195 F*0:REM INITIALIZE END FLAG

197 IK=0:REM INDEX KEY INITIALIZE

200 FOR L=0 TO 1?

205 IF F=1 THEN GOSUB 9200:G0TO 2?0sREM END HAS BEEN FOUND ALREADY

215 IF PEEK(H+L*40*2)*134 THEN F=1:G0T0 2?0:REM THIS IS THE FREE TRACK LINE

220 POKE M+L*40,L*1 29:REM THIS IS THE INDEX LETTER

230 POKE HU*40*1,JI:REH THIS IS A V

290 NEXT L

294 L*L+1 : GOSUB 9200

300 IF F=1 THEN lOOOsREM SKIP SECOND COLUMN - ALREADY DONE

305 M=32?07: IK=0:REM SECOND COLUMN

310 FOR L=0 TO 5:REM FOR UVUXYZ

320 IF F* 1 THEN GOSUB 92O0:GOTO 390

330 IF PEEK(M+L*40*2)=134 THEN F-1 :GOTO 390

340 POKE HU*40,LH4?:REM THIS IS THE INDEX LETTER

350 POKE M+LMO+1 ,31 :REH THIS IS A

390 NEXT L

400 IF F=1 THEN 1000:REM END FOUND ALREADY
410 FOR L»6 TO 15.-REM FOR 0123456789
420 IF F=1 THEN GOSUB 9200:GOTO 490

430 IF PEEK(M+L*40+2)«I34 THEN F*1:G0TQ 490:REM END FOUND
440 POKE M*L*40,L*170:REM THIS IS THE INDEX NUMBER
450 POKE M*L*40*1 ,31 :REH THIS IS A
490 NEXT L

500 IF F*1 THEN 1000:REM END FOUND ALREADY
510 FOR L=16 TO 18:REH FOR *«

520 IF F=1 THEN GOSUB ?200:G0T0 590

530 IF PEEK(M+L+40+2)=134 THEN F= 1 : GOTO 5?0:REM END FOUND
540 POKE N+L*40,L*147:REM THIS IS THE INDEX CHARACTER
550 POKE M*L*40*1 ,31 :REM THIS IS A
590 NEXT L

1000 GET AAt : IF AA« = U " THEN IOOOjREM GET CHOICE
1010 IF AA*="*" THEN 9990

1020 IF AA$ a “>" THEN D=2-D+1:GQT0 20:REM CHANGE DRIVES
1100 A=ASC( AAi)

1200 IF A>64 AND A<85 THEN H=32890:L=A-65:G0T0 1300:REM SKIP 2ND COLUMN

1205 M=3290?:REM FOR SECOND COLUMN

1210 IF A>=85 AND A<=90 THEN L*A-65-20:G0T0 1300

1220 IF A>=48 AND A<=57 THEN L=A-42:G0T0 1300:REM F0R0123456789

1230 IF A>=35 AND A<»37 THEN L=A-19:G0T0 1300

1240 PRINT "IHOHEK 3 RIGHT3CRVS3PLEASE CHOOSE ONLY AN INDEX LISTEDC0FF3"

1250 GOTO 1000
129? END

1300 F«="“;RV=0:REM INITIALIZATION

1305 PRINT “CHOMEK 23 D0UN3E 3 RIGHT3>»»»»»»CRVS]HERE IT COMES... I0FF3"

1310 FOR K=0 TO 15

1320 FL=PEEK(M*L*40*K) :REM VALUE OF CHARACTER

both Dr. Daley (425 Grove Ave.,
Berrien Springs MI 49103) and
Sawyer Software (201 Worley
Rd., Dexter MO 63841). Business
Software for the Commodore
disk is available from both NEE-
CO and CMS Software (5115
Menefee Dr., Dallas TX 75227).
Next time I hope to have more in-
formation on these.

It appears that both Dr. Daley
and Programma International
(3400 Wilshire Blvd., Los Angeles
CA 90010) are offering programs
on Computhink diskettes as well
as on cassettes. (A software an-
nouncement for Programma in
Micro mentioned this, and Dr.
Daley notes this option in his bro-
chures.) TIS (PO Box 921, Los
Alamos NM 87544) has just an-
nounced that their text-editing
program, MEDIT, is now avail-
able for use with Commodore
disk and printer. It is priced at
$12.95 and includes an over-40-
page manual. It will be interesting
to see which disk system will be
supported by each of the many
PET companies.

New PET to Printer Update

The new PET is a big improve-
ment over the old PET. I haven’t
yet used a PET printer, but I’m
told that it can print uppercase
and lowercase letters as they ap-

1322 IF FL> 1 28 AND RV=0 THEN GOSUB 9000
1324 IF FLOJfl AND RV=1 THEN GOSUB 9500
1326 IF FL>1 28 AND RV=2 THEN GOTO 9600

pear on the screen. I don’t know
why Commodore didn’t do this in

1328 IF FL> 1 28 AND RV=1 THEN FL=FL~128

1330 GOSUB 8000:REM CONVERT TO STRING CHARACTER

1390 NEXT K

2000 IF RV THEN GOSUB 9700
2010 »X,D,F«

8000 REM CONVERT PEEK TO CHR*

8002 REM FL IS PEEK VALUE

8004 REM FT IS CONVERTED FOR CHR*

8006 REM F$ IS THE STRING CHARACTER
8010 IF FL>«0 AND FL<*31 THEN FT=FL+64
8020 IF FL«>32 AND FL<«63 THEN FT=FL
8030 IF FL>*64 AND FL<=?5 THEN FT=FL+128
8040 IF FL>*?6 AND FL<*127 THEN FT*FL+64
8100 IF FL< 1 28 THEN FH*CHRt(FT) sGOTO 8800
8800 REM FI * IS CHR* FOR THIS CHARACTER POKE
8810 F$=F$+F1 ♦

899? RETURN

9000 RV=1 :REM REVERSE FOUND
9010 F$=F$+"CRVS3"

9020 FL-FL-128
909? RETURN

9200 IF IK a 1 THEN 929?

9210 IK=1

9215 POKE M+L*40-40,30:REM *

9220 POKE MH*40,137:REM I
9225 POKE M*L*40*1,142:REM N
9230 POKE M*L*40+2,132:REM D
9235 POKE M*L*40*3, 133:REM E
9240 POKE M+L*40*4, 1 52 : REM X
9245 POKE M*L*40+5, 160:REN
9250 POKE H+L*40+6, 1 39:REN K
9255 POKE M+L*40*7,133:REM E
9260 POKE H+L*40*8,153:REM Y
9299 RETURN

9500 RV«2:REH REVERSE FOUND AND TURNED OFF
9510 F$=F$*“C0FF] M
959? RETURN

9600 PRINT "IHOMEH 2 RIGHT3ERVS3YOUR FILE NAME IS TOO CONFUSING FOR MEC0FF3"
9610 GOTO 1000
9700 F$=LEFT$(F>,I6)

979? RETURN

9990 PRINT "CHOMEK 21 D0UN3"

9992 POKE 525,9

9994 POKE 527, 1 4 5 : REM UP

9996 FOR Z=528 TO 533sP0KE Z ,32 :NEXT Z:REM SPACE
9998 POKE 534, 1 45s POKE 535,141 :REM SHIFT RETURN
999? END

their 2040-floppy manual. The
good news on the manual is that it
is only temporary; a final im-
proved version is now being com-
pleted. There’s a problem in us-
ing a printer such as the Teletype
43 via RS-232. Apparently the old
PET did not use true ASCII code,
and the RS-232 interfaces cor-
rected for this. The new PET
sends true ASCII code, which is a
good improvement, but either the
interface made for the old PET
will have to be modified or a pro-
gram written to convert upper-
case to lowercase. If anyone has
the answer, please contact me.

Upgrades for Old PET

Old-PET owners now may buy
a set of new ROMs for their old
PET. There are two types of
ROMs. Both are packaged in a set
of seven ROMs and are priced at
$89.95 per set from Commodore
(3330 Scott Rd., Santa Clara CA
95050). To upgrade your old
PET, simply remove the old ROM

Menu program (contact author — not c/o Microcomputing, please— for missing part of line 110).

set and replace it with the new

18 Microcomputing, October 1979

OUR VISIBLE MEMORY ADDS FUNCTION
AND FUN TO YOUR 6502

This DOT MATRIX display board doubles as an 8K MEMORY.
You can use it as a display, memory expansion or both with
graphic and text display software available. You get resolution
graphics with no wait states, no snow, and no processor
overhead. K-1008 ASSEMBLED and TESTED $240.00, BARE
BOARD $40.00 K-1008-1 GRAPHICfTEXT UTILITY SOFTWARE
LISTING $20.00.

As a dot matrix formatted 200 high by 320 wide, it allows high
resolution patterns to be displayed and evaluated. It enhances
system performance for data acquisition displays, math equa-
tion plotting, etc.

For charts and graphs, it is valuable in the educational,
research and business fields. Shown to the right is a single
period of a complex frequency waveform and its frequency
spectrum chart.

For text display, dot matrix is the ultimate. Any character set
the user desires is possible. Even subscript and superscript in
the same column, and— mixed text and graphics. The improved
man-machine interface for an unskilled operator increases pro-
ductivity.

Graphics allows you to program games with much more ac-
curate representation of your game because YOU DETERMINE
THE SHAPES on the display, not a ROM character generator.
Our LIFE program allows tremendous creativity in creating
complex colonies for observation of generation growth and
decay.

Developed by a leading group of New England engineers for in-
terface with the three 6502_KIM BUS systems (KIM, VIM, AIM).
The K-1008 requires only the processor card and its power sup-
ply to function as a memory. Add a monitor and you have
graphics and text display available. Micro Technology also
makes K-1000 Power Supplies, K-1005 Card Files, K-1002 8 Bit
Music Systems (with advanced software), K-1020 Regulated
Wire Wrap card, K-1012 IO/COMM/PROM/270B Programmer
card, K-1016 16K Memory, all sold assembled and tested or as
bare boards. Write for technical information, prices and terms.

Overseas orders— include $3.00 for shipping.

Micro Technology Unlimited

iS M44

P.O. Box 4596 Manchester NH 03108

The way you
check line-by-line with
an A P Intra-Switch or
Intra-Connector.

You plug your Intra-Switch in-line
with standard socket connectors,
and Instantly you've got a separate,
independent on-off switch for each
and every line in your flat ribbon
cable. To switch, you nudge with a
pencil point. It's that quick.

Imagine how much time and
trouble Intra-Switch will save you in
your diagnostic and quality testing,
your programming and selective
line inhibiting.

Or, plug in your Intra-Connector
(see box) the same way, and you
have an extra set of male contacts

at right angles. Instant line-by-line
probeability— and an easy way to
tap your system and daisy chain it
into new areas.

Both Intra-Connectors and Intra-
Switches come In 20, 26, 34, 40 and
50-contact models.

Where? At your nearby A P deal-
er. Where’s that? Phone (toll-free)
800-321-9668. And ask for the com-
plete A P catalog, The Faster and
Easier Book.

AP PRODUCTS
INCORPORATED ^ A22
Box 110 E» 72 Corwin Drive
Painesville, Ohio 44077
Tel. 216/354-2101
TWX: 810-425-2250

Faster and Easier is what we're all about.

iS Reader Service— see page 227

Microcomputing, October 1979 19

ROM set. Once upgraded, your
old PET will use the same mem-
ory locations as a new PET.
Thus, most PEEK or POKEs
used in old PET programs will
not function properly and may
even lock out your PET. You can
modify your programs using my
conversion chart starting on p. 72
of the July issue of Microcomput-
ing. Since programs using ma-
chine-language subroutines prob-
ably won’t work with the new
ROM upgrade, what becomes of
your old ROM set? Do you throw
it away?

Small System Services, Inc.
(900 Spring Garden St., Greens-
boro NC 27403), has what seems
to be an excellent answer to this.

question: a small board that plugs
into your ROM sockets. It comes
completely assembled for $54.95
and is easy to hook up. Both your
old and new ROMs plug into the
board, and can be activated with
the flip of a switch.

This board is called the Basic
Switch. For $149.95, SSS will send
it to you with the new ROMs al-
ready in the correct sockets, mak-
ing it even easier for you, plus
saving you $5 over purchasing the
new ROMs directly from Com-
modore. A deluxe model will be
available with an extra socket or
two. You can plug the Program-
mer’s Tool Kit or other software
on ROM into these sockets. For
more details, contact Small Sys-
tem Services.

(Special note: There are two
different types of old ROMs. The
new upgrade for the old 6540 set
is available now. The new up-
grade for the old 6316 set should
be available in August. If you
order the Basic Switch, be sure to
specify your PET serial number
and the type of old ROM in your
PET so SSS can send you the cor-
rect version of their board. You
should also know that the Basic
Switch board doesn’t connect to
any of the PET expansion ports,
which might be a problem
for those with things already at-
tached. Anyone upgrading his
old PET directly with ROMs and
not using the Basic Switch should

save his old ROM set. Who knows
—maybe someone will put out a
board for the new PET allowing
it to use the old ROMs.)

Program Protection Encore

Many software companies are
concerned about illegal copying
of their programs and are now at-
tempting to protect their pro-
grams from being copied. Com-
puthink has a method to protect
disk programs with their disk sys-
tem. I’ve also discovered an easy
method with their system. Of
course, I won’t tell you how it’s
done, but any software marketer

is welcome to contact me, and I
can send an example. CMS Soft-
ware has developed a method of
protection using the PET disk
system. NEECO also has worked
on a protection method.

CMS Software

CMS Software is now offering
several comprehensive business
software packages for the PET
with Commodore dual disk drives.
They also are looking for special-
ized programs to use with their
accounting packages. CMS will
supply all the subroutines and
pay royalties up to 60 percent. I
was fortunate to receive a prelim-
inary version of the CMS General
Ledger. The diskette with docu-
mentation has an announced
price of $295. Also announced at
$295 each are Payroll with Cost
Accounting and Accounts Pay-
able/Accounts Receivable. Con-
tact CMS Software for the name
of your nearest dealer.

Software for Schools

Conduit (PO Box 388, Iowa
City IA 52240) has 11 software
packages in physics, biology and
chemistry on cassette for the
PET. These programs are de-

scribed in detail in Pipeline , Vol.
4, No. 2. Pipeline is available free
from Conduit. Simply send a
postcard and ask to be placed on
their mailing list.

Microphys Programs (2048
Ford St., Brooklyn NY 11229)
has announced nearly 100 pro-
grams in various subjects, mainly
for high schools. Subjects in-
cluded are chemistry, physics,
utilities, math and vocabulary.
Several of these programs are
also being offered by Commo-
dore. Some of the programs are
computer assisted instruction,
while others are individualized in-
struction.

Programs from both Conduit
and Microphys should prove use-
ful in the classroom. Commodore
also has announced programs for
educators. Their programs in-
clude a series in elementary lan-
guage arts written by Thorwald
Esbensen. I hope to see these
soon. I have seen other programs
by Mr. Esbensen, and he does a
wonderful job of making them
both instructional and interesting
for children.

Hardware Reset

International Technical Systems
(Box 264, Woodbridge VA 22194)
is selling a little device consisting
of a push button, which mounts
on the side of your PET, and two
alligator clips that “hook” onto
two locations inside the PET. It
installs easily . . . one push of
the button and your BYTES
FREE message is back on the
screen. This is useful if you are
doing machine-language program-
ming and you are “locked out.”
With this button, you won’t have
to turn your PET off and back
on, which is hard on your moni-
tor. A touch of the button resets
the PET and clears all memory,
and apparently the cassette buf-
fers are left intact— a good side
benefit.

Cassette Tape Sources

I’ve received favorable com-
ments on the following com-
panies’ cassettes (please write
with your notes on both good and
bad cassettes for use with the
PET):

Dr. Daley, 425 Grove Ave., Ber-
rein Springs MI 49103.

AB Computers, PO Box 104,
Montgomeryville PA 18944.
Computer Applications, Box
203, 446 Newbridge Ave., East

Meadow NY 11554.

DAK Industries and Long
Electronics have been
mentioned, but I have no ad-
dresses to list.

Stop Key Disable

To disable the STOP key, your
program will have to determine
on which version of PET it is run-
ning. A PEEK at location 50003
will confirm whether it’s a new or
an old PET. A new PET will re-
turn a 1, while the old PET will
return a 0. See my article on p. 72
of the July issue for a discussion
on using this information. Briefly,
the following line will allow you
to use variable PT as the PET
Type: 0 PT = PEEK(50003).

To disable the STOP key on the
old PET, POKE 537,136; on the
new PET, POKE 144,49. Micro
Software Systems (PO Box 1442,
Woodbridge VA 22193) was kind
enough to supply the following
modification of my one-line
STOP disable (July issue). If exe-
cuted more than once, my version
could cause loss of control. Their
version is shown in Example 1.
To reenable the STOP key, use
Example 2. If you previously as-
signed PT and SL, you need not
repeat the first section of the re-
enable line. You could then sim-
ply use: 900 DL = 133-87*PT:
POKE SL,DL.

These lines will operate on
either old or new PETs without
modification since the lines are
“smart” and “know” which PET
they are running on. There are
possible side effects with this
method, however. I believe it
messes up the PET jiffy counter.
If your program uses it, you may
have to either change that section
of your program or use another
method of STOP disable.

Macro Assembler/Text Editor

This assembler from C. W.
Moser (3239 Linda Dr., Winston-
Salem NC 27106) is written entire-
ly in machine language, not in
BASIC as others for the PET
often are. Thus you get fast and
accurate assemblies. It is an 8K
program, so you need at least
some memory expansion for your.
8K PET to be able to use this pro-
gram. It features 26 commands, 22
pseudo ops and 36 error codes. In-
cluded are vectors and special
commands for use with disk op-

(see PET-POURRI, page 190)

1 PT = PEEK(50003):SL = 537-393*PT:DL = 136-87*PT:POKE SL, DL

Example 1.

900 PT = PEEK(50003):SL = 537 - 393*PT:DL = 133 - 87*PT:POKE SL, DL

Example 2.

20 Microcomputing, October 1979

NEW PRODUCTS

Edited by Dennis Brisson

TRS-80 Minifloppy Disk Drive

Percom Data Co., 211 N.
Kirby, Garland TX 75042, is
advertising a TRS-80-compatible
add-on minifloppy disk drive.
You can purchase a single, double
or triple disk-drive unit to expand
your present system. You will need
an expansion interface, TRSDOS
diskette and TRSDOS manual to
use the Percom drives. These same
items are required to run the
Tandy (Radio Shack) disk drives.

Instant Software, Inc. (ISI),
purchased a triple drive unit,
which arrived with three Wangco
Model 82 disk drives (Pertec FD
200 disk drives are also used), a
cabinet with power supplies, a
new ribbon interconnect cable,
a MICRODOS diskette and
MICRODOS manual. Each disk
drive is packed separately, and
you have to assemble the units into
the case. The only tool we needed
was a straight-blade screwdriver.
The disk drives were ready to be
connected to the TRS-80 in about
half an hour.

The best surprise came when we
tried to run the system. All three
disk drives functioned properly
right from the start. We had a
Tandy single drive that we sent
back to Tandy three times before it
functioned correctly. The Wangco
drives are slower (40 millisecond
track access time) than the Shugart
drives used by Tandy, but the time
difference is not a significant fac-
tor during operation. Data trans-
fer to and from the disk drives has
been solid and error free.

The MICRODOS is a simple,
yet versatile, disk operating system
for the TRS-80, but it is not com-
patible with TRSDOS. MICRO-

Percom *s TRS-80 triple drive unit.

DOS is composed of four pro-
grams: a menu, a simple disk file
manager, disk utilities (which in-
clude backup, erase and copy) and
the Percom notebook. One of the
niceties is a merge command that
will merge a routine from disk into
a program in memory. This allows
building an extensive subroutine
file on disk and merging into the
program. You write the subrou-
tine once and then call it up
anytime you want it.

ISI did have one problem with
the Wangco drives. There is an in-
terlock device in these drives that
we were activating by finger to get
the door closed. The disk drives
are mounted on edge in the Per-
com housing unit. With the hous-
ing on its side, the disk drives are
horizontal with their doors open.
In this position the interlocking
device started working properly.
This particular door interlock re-
quires proper orientation to func-
tion, but this in no way impairs the
use of the drives. We overcame the
problem of the sticking door inter-
lock.

That the Percom system func-
tioned properly the first time is
recommendation enough, but
couple that with MICRODOS and
its low cost, and you have a good
system for the money. Reader Ser-
vice number P64.

Edward E. Ulmer
Technical Dept., ISI

Imagination Machine

The Imagination Machine is a

Apple II Business System.

personal computer and home en-
tertainment center in one. It can be
used for educational guidance,
home and personal-budget man-
agement, as well as for leisure-time
activities such as games of skill,
chance, dexterity and multi-player
competition.

Through a simple hookup with
your existing TV set, you can start
up your Imagination Machine,
which is user programmable. At
high resolution, the system’s color
graphics consist of 128 x 192
characters with up to eight color
variations.

Standard features include 10K
ROM and 9K RAM memory,
typewriter-type keyboard, 53 keys
with a unique shifted “BASIC
Keywords’’ button, two game-
style controllers, 32 characters x
16 lines screen format, six function
built-in cassette tape deck, digital
and audio information record/
playback, built-in microphone
jack, cartridge connector plus an
internal operating system and

APF r s Imagination Machine.

BASIC interpreter.

The Imagination Machine has a
built-in music synthesizer with a
range of three octaves including
sharps and flats. Expandable op-
tions include printers, floppy
disks, word-processing capa-
bilities and expandable RAM plus
coupler modems.

APF Electronics, Inc., 444
Madison Ave., New York NY
10022. Reader Service number
A103.

Business System

The Apple II Business System
combines all the advantages of a
personal computer — portability,
accessibility and affordability—
with versatile business software. !
The configuration includes the
Apple II Plus Computer, which is
an upgrade of the Apple II first
sold in 1977, 48K bytes of RAM
memory, two disk drives, a video
monitor, a printer and the Con-
troller software package.

The system has an expanded
version of built-in BASIC that
makes it well suited for business
problem solving. In addition, an
Auto-Start ROM chip provides
automatic disk loading as the
system turns on, reset protection
and easy screen editing. The Con-
troller business software package,
designed especially to meet the
needs of smaller businesses, con-
sists of three program modules:

In our July 1979 mention of \
Microsoft y s M6800 BASIC (p.

16), we failed to state that the
BASIC is licensed only on an
OEM contract basis; it is not now
directly available to end users.

General Ledger, Accounts Re-
ceivable and Accounts Payable.

The Controller package in-
cludes a unique fail-safe feature of
the data entry system that signals
typing errors with an audible
warning. The Controller auto-
matically makes copies of data
files for historical purposes in case
of lost originals and automatically
prints reports before the system
will allow the user to close out the
monthly books. The system costs
$4995.

Apple Computer, Inc., 10260
Bandley Drive, Cupertino CA
95051. Reader Service number
A28.

Graphics Digitizer

The Simple 11 is a new digitizer
aimed at systems with graphics ap-
plications ranging from medical
analysis to interactive graphics to
engineering design. The Simple II
is an 1 1 x 11 inch self-contained
digitizer with 400 lines per inch
resolution and 10 mil accuracy.
X-Y output is variable up to 240
coordinate pairs per second.

The Simple II, from Talos Sys-
tems, Inc., 7419 E. Helms Dr.,
Scottsdale AZ 85260, will replace
the Simple One as the firm’s small
low-priced graphics digitizer. The
new unit will sell for $1065. The
Simple II will not replace the 600
series digitizers the firm currently
offers, but will serve where high
resolution, backlighting or rear
projection are not necessary.
Reader Service number T70.

Digitized Audio Response System

The Votrax LVM-80 is a solid-
state multiplexed audio response
system that provides multi-line
audio output and Touch -Tone in-
put handling capability for micro-
computers, minicomputers and

large business mainframes. The
vocabulary capacity of the
LVM-80 is 512 seconds of speech,
or approximately 1024 individ-
ually addressable messages.
Memory capacity of the LVM-80
is 16K (EPROM) and can be
erased and reused should the user
require reprogramming of the
vocabulary by Votrax.

The LVM-80 communications
processor services up to 64
simultaneous telephone lines and,
through a process of digitizing ac-
tual human speech, can “speak”
words and phrases with a quality
that is virtually indistinguishable
from the original speaker.

Votrax, 500 Stephenson High-
way, Troy MI 48084. Reader Ser-
vice number V26.

Video Display Board

The Electric Window video dis-
play board is memory-resident,
programmable and displays up to
24 80-character lines. Named the

Exidy 's Video /Disk.

Electric Window because the gen-
erated display is like a window
through which you can observe the
memory space where characters
are being input and manipulated,
this product is convenient in all ap-
plications, but has particular value
in text and word processing where
the effects of editing and line
justification are instantly visible.

Electric Window features in-
clude: two character generators—
one for standard characters and
one that can be programmed for
special characters— dual intensity,
highlighting alphanumeric dis-
play; display scrolling controlled
by a single programmable register;
descenders on lowercase letters for
improved readability; program-
mable display positioning; and
programmable interlaced or non-
interlaced scan. The Electric Win-
dow is compatible with standard
video monitors. The instruction
manual supplied with the Electric
Window includes a complete op-
erating system listing. An optional
PROM operating system is also
available. The Electric Window

costs $249.95.

Percom Data Company, Inc.,
21 1 N. Kirby, Garland TX 75042.
Reader Service number P62.

Video/Disk for the Sorcerer

A new Video/Disk peripheral
attachment for the Sorcerer com-
puter from Exidy Data Products,
390 Java Drive, Sunnyvale CA
94086, contains a 12 inch video
display and dual mini-floppy disk
drives with data storage capacity
of 630,000 words. The swivel-
based unit attaches directly to the
Sorcerer’s keyboard enclosure to
form a desktop computer system
no larger than a video terminal for
small-business data processing.
The disk drives utilize a unique
precision metal positioner to
achieve their storage capacity.

The high-performance video
display utilizes a P3 1 phosphor for
readability and a 20 MHz band-
width for clear pictures to easily
handle computer generation of
240 x 512 graphic resolution.
Software included with the hard-
ware consists of the popular
CP/M operating system, Z-80 as-
sembler, text editor, linking loader
and Microsoft Disk Extended
BASIC. The Exidy Video/Disk
costs $2995. Reader Service
number E44.

Microcomputer Modem

The Micromodem 100, a com-
plete data communications system
for S-100 microcomputers, com-
bines on a single board functions

that formerly required a modem,
an automatic calling unit and
serial and parallel interfaces. The
new board is a sophisticated com-
puter-to-computer or terminal-to-
computer modem for small com-
puter systems.

The Micromodem 100, fully
S-100 bus compatible, including
16-bit machines and 4 MHz pro-
cessors, converts digital data into
analog signals for transmission
over regular voice telephone lines.
Because it is a Bell System 103
compatible modem, it can com-
municate with the most commonly
used modems in North America. It
operates at either of two software-
selected baud rates— 300 baud and
a jumper-selectable speed from 45
to 300 baud— and is equipped with
an FCC registered Microcoupler
data access arrangement that feeds
the signal into the telephone line
through a modular connector pro-
vided by the local telephone com-
pany. Because of this direct con-
nect feature, the Micromodem 100
can automatically answer the
phone or dial a number. The
Microcoupler provides direct ac-
cess to the telephone system with-
out the losses or distortions asso-
ciated with acoustic couplers and
without a telephone-company-
supplied data access arrangement.

The Micromodem 100 serves as
a convenient data communica-
tions tool between home and of-
fice, an automatic data collector
from remote terminals, an intelli-
gent terminal and allows imple-
mentation of remote software
maintenance and customer sup-
port. It sends programs, letters
and other data over the telephone
and provides access to remote data
bases. It is software compatible
with the D. C. Hayes Associates
80- 103 A Data Communications
Adapter, but offers improved per-
formance and a direct connect and
receive sensitivity of - 50 dBm.

D. C. Hayes Associates, Inc.,

The VDB-1 Smoke Writer.

The Micromodem 100 and Microcoupler.

16 Perimeter Park Drive, PO Box
9884, Atlanta GA 30319. Reader
Service number H20.

Smoke Writer

The VDB-1 Smoke Writer is a
fast SS-50 bus video display board
featuring the MC6845 CRT con-
troller chip to provide total control
over display formats. The new
board controls an 80 x 24 display
with 32 graphic characters and has
upper and lowercase characters
with lowercase descenders. 128
character graphics are optional.
Its programmable character set, a
total of 128 characters, is in a 2K
EPROM with 256 character 4K
EPROM optional.

The Smoke Writer video
board’s other important features
include: reduced intensity or
reversed video, programmable
display rate (10-5000 characters
per second), protected fields, ad-
dressable cursor, 2K video display
RAM accessible by the CPU as
standard RAM memory, 128 bytes
of scratchpad RAM and IK
EPROM for software drivers.
Either a business program that
needs protected fields or a cursor-
based editor application will make

The Boris Diplomat.

good use of this video board. Price
is $349.

Smoke Signal Broadcasting,
31336 Via Colinas, Westlake
Village CA 91361. Reader Service
number S46.

Battery-Operated
Chess Computer

The Boris Diplomat is a full-fea-
tured, microcomputer-based chess
computer that is designed for
travel. It is compact (8x7xl!/2
inches), portable and battery op-
erated (operates several hours on
six AA batteries, not included, or
on the ac adapter, included), with
a built-in chessboard with pieces.

Designed with various opera-
tional strengths, the Diplomat will
play at a level that will teach a
child or will keep the attention of a
master. As a teacher, it suggests
moves for the unsure beginner.
The position programmer allows
more advanced players to set up
special board positions to practice
specific strategies. Beginners can
use the position programmer to re-
move pieces for handicapping or

for practicing specific positions.
Price is $1 19.95.

Chafitz, Inc., 1055 First Street,
Rockville MD 20850. Reader Ser-
vice number Cl 5 1 .

Computer and Terminal in One

NCE/CompuMart, PO Box
8610, Dept. PI, Ann Arbor MI
48107, combining the PET com-
puter and NCE’s own design in a
direct spin-off from the PET tech-
nology, announces the TC 2001 , a
computer and a terminal in one
unit at a price lower than a ter-
minal alone. The TC 2001 func-
tions as a full duplex, dumb ter-
minal that can be used in con-
junction with remote timesharing
services, and also as an advanced
personal computer. It incor-
porates one of today’s most pop-
ular microprocessors, the MOS
6502, for fast and reliable opera-
tions. It is available with 8K, 16K
of RAM memory. The ROM
memory size is 14K. The TC 2001
uses BASIC language (Level II)
and is fully expandable through
IEEE, TTL parallel, second cas-

The TC 2001.

Microcomputing, October 1979 23

Welcome to Percom’s Wide World

Each LFD mini-disk storage system
includes:

• drives with integral power
supplies in an enamel-finished
enclosure

• a controller/interface with ROM
operating system plus extra ROM
capacity and 1 K of RAM

• an interconnecting cable

• a comprehensive 80-page users
manual

the Size You Want

Percom LFD mini-disk drive
systems are supplied complete
and ready to plug in the moment
they arrive. You don’t even have
to buy extra memory. Moreover,
software support ranges from
assembly language program
development aids to high-speed
disk operating systems and
business application programs.

The LFD-400® and -400EX® systems
and the LFD-800™ and -800EX systems
are available in 1*-, 2- and 3-drive
configurations. The -400, -400EX drives
store 102K bytes of formatted data on
40-track disks, and data may be stored on
either surface of a disk. The -800, -800EX
drives store 200K bytes of formatted data
on 77-track disks.

The LFD- 1000- systems (not pictured)
have dual-drive units which store 800K
bytes on-line. The LFD-1000~ J controller
accommodates two drive systems so that
a user may have as much as 1 .6M bytes
on-line.

Mini-disk storage system prices

1 -DRIVE
SYSTEM

2-DRIVE

SYSTEM

3-DRIVE

SYSTEM

MODEL

For the SS-50 Bus:
LFD-400™

LFD-800®

For the EXORciser* Bus
LFD-400EX®
LFD-800EX'"

LFD-1000®

$1449.95

2245.95

$ 649.95 $1049.95

945.95 1599.95

(dual) $2495.00 (quad) $4950.00

• 800EX ® Systems

EXORciser Bus LFD-400EX,

Data Terminal & Two-Cassette
Interface — the CIS-30+

terminal

line

auto

local

mw m

• Interface to data terminal and two cassette recorders
with a unit only 1/10 the size of SWTP’s AC-30.

• Select 30, 60 or 120 bytes per second cassette
interfacing; 300, 600 or 1200 baud data terminal

interfacing.

• Optional mod kits make CIS-30 + work with any
microcomputer. (For MITS 680b, ask for Tech Memo
TM-CIS-30-t- -09.)

• KC Standard/Bi-Phase-M (double frequency) cassette
data encoding. Dependable self-clocking operation.

• Ordinary functions may be accomplished with 6800
Mikbug* monitor

Prices: Kit, $79.95; Assembled, $99.95. Prices include
a comprehensive instruction manual. Also available: Test
Cassette, Remote Control Kit (for program control of
recorders), 1C Socket Kit, MITS 680b mod documentation
and Universal Adapter Kit (converts CIS-30 + for use with

Upgrade to 6809 Computing Power. Only $69.95

Although designed with the SWTP 6800 owner in DIP header, and re-inserting the orig
mind, this upgrade adapter may also be used with components. Also available for your

most other 6800 and 6802 MPUs. The adapter is system is PSYM0hP J (Percom SYst

supplied assembled and tested, and includes the the operating system for the Percom

6809 1C, a crystal, other essential components and single-board computer. PSYM0N®

user instructions. Restore your original system by costs only $69.95. On diskette (sour

merely unplugging the adapter and a wire-jumpered files), only $29.95.

any computer).

SS-50 Bus LFD-400 ®. and LFD -800 m Systems

of 6800 Microcomputing

And ‘looking into’ is just what
you do with the Electric
Window® as you peer right
into memory space where
characters are being input
and manipulated. Display
is memory-resident,
programmable and generates
up to 24 80-character lines.
Other features include:

• standard character
generator plus provision for
optional special character
generator

• dual intensity, high-lighting
alphanumeric display

• scrolling by a programmable
register • programmable
display positioning

• programmable interlaced or
non-interlaced scan

• descenders on lower case
letters • users manual with
application instructions and
listing of WINDEX® driver.

The Electric Window.® "

Worth Looking Into. $249.9$'

WINDEX® is a fast video display driver program for
the Electric Window®. WINDEX® also features:
program and keyboard control of character
generators • displayable control characters — under
program control • automatic scrolling • a driver
routine for the parallel input keyboard feature of the
Percom 6809 Single-Board Computer, the SBC/9®

• auto-linking to PSYMON®, the ROM operating
system for the SBC/9® • Prices: ROM version:
$39.95; LFD-400® compatible diskette (source and
object files): $29.95.

PDQ from PDC!

In the product development queue and available soon: the SBC/!}*

stands alone as a control computer, but also

(Single-Board-Computer/6809)
compatible with the SS-50 bus for use as an MPU card. Includes PSYMON® (Percom
SYstem MONitor) in a IK ROM and provides for additional IK of ROM. Also includes IK
of RAM. Features: Super Port — provision for multi-address, 8-bit bidirectional data
lines • an intelligent data bus for multi-level data bus decoding • an on-board 110-baud
to 19.2 kbaud clock generator • extended address capability — to 16 megabytes —
without disabling baud clock or adding hardware. And much more. Supplied with
PSYMON® and comprehensive users manual. Price $199.95.

Full Feature Prototyping PC Boards

All of the features needed for rapid,
straightforward circuit prototyping. Use
14-, 16-, 24- and 40-pin DIP sockets
• SS-50 bus card accommodates 34- and
50-pin ribbon connectors on top edge,
10-pin Molex connector on side edge* I/O
card accommodates 34-pin ribbon
connector and 12-pin Molex on top edge

• I/O card is t-% inches higher than
SWTP I/O card • interdigitated power
conductors • contacts for power regulators
and distributed capacitance bypassing

• use wire wrap, wiring pencil or solder
wiring • tin-lead plating over 2-oz copper
conductors wets quickly, solders easily

• FR4-G10 epoxy-glass substrate.

To place an order or request additional literature call toll-
free 1-800-527-1592. For technical information call (214)
272-342 1 . Orders may be paid by check, m mey order, COD or
charged to a VISA or Master Charge accou it. Texas residents
must add 5% sales tax.

PRICES AND SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE.

PERCOM DATA COMPANY. INC.
211 N. KIRBY GARLAND TEXAS 75042
C214) 272-3421

6800/6809 SOFTWARE
System Software

6800 Symbolic Assembler — Specify assembly options
at time of assembly with this symbolic assembler. Source

listing on diskette $29.95

Super BASIC — a 1 2K extended random access disk BASIC
for the 6800 and 6809. Supports 44 commands and 31 func-
tions. Interprets programs written in both SWTP 8K BASIC
(versions 2.0, 2.2 & 2.3) and Super BASIC. Features: 9-digit
BCD arithmetic, Print Using and Linput commands, and much

more. Price $49.95

TOUCHUP® — Modifies TSC’s Text Editor and Text Pro-
cessor for Percom mini-disk drive operation. Supplied on

diskette complete with source listing $17.95

Operating Systems

INDEX® — This easy-to-use disk-operating and file man-
agement system for 6800 microcomputers is fast. I/O devices
are serviced by interrupt request. INDEX® accesses peripherals
the same as disk files — new devices may be added without
changing the operating system. Other features: unlimited
number of DOS commands may be added* over 60 system
entry points • display only those files at or above user-specified
file activity level • versions available for SWTP MF-68, Smoke’s

BFD-68 and Motorola’s EXORciser*. Price $99.95

MINIDOS-PLUSX® — An extension of the original
MINIDOS® for LFD-400® mini-disk systems, MINIDOS-

PLUSX® manipulates files by six-character names. Supports
up to 31 files. Resident commands include Initialize, Save,
Allocate, Load, Files (directory list), Rename and Delete.
Supplied on 2708 ROM with a minidiskette that includes
transient utilities such as Copy, Backup, Create, Pack and Print

Directory. Price $34.95.

PSYMON® — Percom SYstem MONitor for the Percom
single-board/ SS-50-bus-compatible 6809 computer accom-
modates user’s application programs with any mix of peripher-
als without modifying programs. PSYMON® also features
character echoing to devices other than the communicating
device, sophisticated register and memory dump routines and

more. Price (on 2716 ROM) $69.95.

WINDEX® — Described in detail elsewhere on this page.
Business Programs

General Ledger — For 6800/6809 computers using Per-
com LFD mini-disk storage systems. Requires little or no
knowledge of bookkeeping because the operator is prompted
with non-technical questions during data entry. General Ledger
updates account balances immediately — in real time, and will
print financial statements immediately after journal entries. User
selects and assigns own account numbers: tailors financial
statements to firm’s particular needs. Provides audit trail. Runs
under Percom Super BASIC. Requires 24K bytes of RAM.
Supplied on minidiskette with a comprehensive users manual.

Price $199.95.

FINDER® — This general purpose data base manager is
written in Percom Super BASIC. Works wth 6800/6809 com-
puters using Percom LFD-400® mini-disk drive storage sys-
tems. FINDER® allows user to define and access records using
his own terminology — customize file structures to specific
needs. Basic commands are New, Change, Delete, Find and
Pack. Add up to three user-defined commands. FINDER plus
Super BASIC require 24K bytes of RAM. Supplied on minidisk-
ette with a users manual. Price $99.95

Mailing List Processor — Powerful search, sort, create
and update capability plus ability to store 700 addresses per
minidiskette make this list processor efficient and easy to use.
Runs under Percom Super BASIC. Requires 24K bytes of RAM.
Supplied on minidiskette with a users manual. Price $99.95.
From the Software Works
Development and debugging programs tor 6800 nCs on disk-
ette:

Disassembler/ Source Generator $30.95

Reloc’tng Disas’mblr/ Segmented Text Gen $40.95

Disassembler/Trace $25.95

Support Relocator Program $25.95

Relocating Assembler/Linking Loader $55.95

SmithBUG** (2716 EPROM) $70.00

V 2 -Price Special on Hemenway Software!

CP/ 68+ disk operating system $ 49.97

STRUBAL+T compiler $124.97

EDIT68 text editor $ 19.97

MACRO-Relocating Assembler $ 39.97

Linkage Editor (LNKEDT68) $ 24.97

Cross Reference utility $ 14.97

^trademark of Percom Data Company, Inc.

* trademark of Motorola Corporation
^Trademark of Hemenway Associates Company

* *SmithBUG is a trademark of the Software Works Company

DATA BNHANCM
□ E-BO

complement number. User-select-
able output ranges of 0 to + 5 V, 0
to +10 V, ±2.5 V, ±5 V and
±10 V are available. The board
may be addressed as I/O ports or
memory mapped. Only four lines
of software are required to pro-
gram these DACs. Price is $395,
assembled and tested.

Tecmar, Inc., 23414 Greenlawn
Ave., Cleveland OH 44122. Read-
er Service number T68.

sette and memory ports. Versions
are available with either a full in-
dustry standard or calculator-type
keyboard, which includes a
cassette drive. Price of the unit
with 8K RAM is $795.

As a terminal, the TC 2001
works at a 300 baud rate. It ac-
cepts RS-232 and outputs TTL
voltage. The TC 2001 has both up-
per and lowercase characters, as
well as graphics, on the 40 charac-
ter by 25 line CRT display. A PET
computer can be converted to
obtain the same terminal capa-
bilities by plugging a module, sold
through NCE for $69, into the
user port. NCE also offers an
acoustic coupler and cable for
both originate and answer mode.
Reader Service number N7.

Data Enhancer

The DE-80 is an attachment be-
tween the Radio Shack TRS-80
and its cassette player to enable
you to read marginally recorded
data over a wide range of volume
settings on the recorder. It will
allow you to read either Level I or
Level II cassettes from a volume
setting anywhere between 4 and 10
on the Radio Shack CTR-type re-
corders, as compared to between 5
to 6 l /i if no enhancer is used in be-
tween. However, the DE-80 can-
not make up for bad recordings or
major tape dropouts where data
has distorted playback wave-
forms, hum and variations in
amplitude.

The DE-80 consists of a small 4
x 2Vi inch box with only the read
wire coming in and out of the box.
It is inserted between the recorder
and TRS-80 so there is no warran-
ty violation from this improve-
ment. The data enhancer also has
an LED lamp that glows when
data is being detected. The LED is
useful for locating gaps between
programs when more than one
program is recorded on the cas-
sette. Price is $45 with the power

The DE-80.

supply included.

Microsette Co., Ill Palomar
Ave., Sunnyvale CA 94086. Read-
er Service number M67.

S-100 EPROM Programmer and
4K/8K EPROM Board

The PB1 programming board
for 2708 and 5 V 2716 EPROMs is
designed to meet all manufactur-
ers* data sheet requirements for
programming 2708s or 2716s. PB1
has two separate programming
circuits so 2708 or 2716 (5 V)
EPROMs can be programmed
without modifying the board.
Two textool programming sockets
are provided for easy insertion and
removal of EPROMs being pro-
grammed. Programming voltage
is generated on-board by a dc-dc
converter — no need for an exter-
nal power supply. Programming
sockets are DIP switch address-
able to any 4K boundary. Special
safety features to prevent acciden-
tal programming include an LED
indicator and an on/off switch for
programming voltage. Software
listings are included for checking
EPROM erasure, programming
and verification.

The board also includes four
additional on-board EPROMs
that are independently addressable
by DIP switch to any 4K (2708) or
8K (2716) boundary above 8000
hex. Unused sockets do not enable
data bus drive. The board is fully
buffered, and 0 to 4 clock cycle

wait states are available. The PB1
has gold-plated edge contacts,
plated through holes, low-profile
sockets and factory prime parts;
the PC board is made of FR-4 blue
epoxy and is solder masked for
ease of assembly. Price is $145,
kit, and $219, assembled and
tested.

Solid State Music, 2116 Walsh
Avenue, Santa Clara CA 95050.
Reader Service number SI 08.

D/A Converter Board

The Tecmar S-100 D/A board
designed for applications requir-
ing high-speed accurate digital-to-
analog conversion, including real-
time applications, supports four
independent high-speed digital-to-
analog converters (DACs) with as-
sociated latches. Each DAC op-
erates completely independent of
the rest. The DACs have a conver-
sion time of three usee, which en-
ables them to operate at maximum
computer speed. A 12 bit latch
drives the inputs of each DAC.
Another four bit latch for each
DAC holds the four new most sig-
nificant bits waiting for the arrival
of the new least significant byte.
This allows the DAC to hold its
previous value until an entire new
word is presented to it.

All the latches are set to zero by
reset. To modify the contents of a
latch, and hence the output of a
DAC, send two bytes to the de-
vice. The input is a 12 bit two’s

Super Isolator

Now you can protect against ex-
treme interference with the Model
ISO-3 from Electronic Specialists,
Inc., 171 S. Main Street, Natick
MA 01760. The Model ISO-3 in-
cludes “superfiltering” for each
of three 3-prong sockets. Heavy-
duty spike and surge suppression
is also included.

Intended for microprocessor in-
stallations in industrial or severe
interference-prone environments,
the Super Isolator also provides
protection against damage from
lightning and electrical machinery
spikes and surges. It connects to
the ac line with a standard 3-prong
plug and can isolate and protect an
1875 Watt total load, with each
socket capable of isolating a 1000
Watt load. Price is $72.95. Reader
Service number E36.

Level II BASIC Shorthand

TSHORT is a Level II BASIC
shorthand that gives you single
keystroke entry for 32 difficult-to-

The Model ISOS.

PB1 EPROM programmer.

Tecmar 's D/A board.

26 Microcomputing, October 1979

type, long and/or repetitive com-
mands. TSHORT saves consid-
erable programming time— up to
90 percent — and, by providing 100
percent accuracy, eliminates the
programmer’s biggest frustra-
tion-syntax errors. Immediately
after each single keystroke entry,
the entire command is spelled out
in its normal format on the moni-
tor and/or listing, i.e., there is no
code to interpret.

TSHORT features a KUSTOM
key, changeable anytime, for user-
defined functions up to 64 char-
acters of instruction, as well as a

self-executing “Go To 10’’ func-
tion (line 10 may contain
“RUN”). TSHORT includes the
most popular and difficult Level II
BASIC commands such as
“RIGHT$(”, “LEFT$(”, “IN-
PUT”, “LPRINT”, “CLOAD”,
“PRINTUSING”, “GOSUB”,
etc.

TSHORT comes on cassette-
one side for Level II and the other
for DOS. What really makes
TSHORT easy to use is the set of
pressure-sensitive decals (white let-

(see PRODUCTS, page 191)

E .

J .

ELSE

LEFT$(

RIGHTS

INTI

LINE

GOSUB

RETURN

DEFUSR

GOTO

SYSTEM

'j*L

G$(

STR$(

CHRS(

VARPTR(

LENl

Keyboard with TSHORT commands.

Overprotective?

I want to comment on the topic
of protected programs. To put
my remarks in context, I should
mention that I am writing and
have programs for sale and have
had articles accepted to be pub-
lished in current trade magazines.
All this means is that I have some
stake in the issue of copyright. No
doubt I would be furious if some-
one copped my programs for his
own and went into competition
with me.

However, there is another side
of the coin that should be consid-
ered before we all go running off
to put a lock and chain on our
programs. I’ve never met a pro-
gram that I have not wanted to
change to meet my own idiosyn-
cracies. Even more important is
that in this industry we have man-
aged to develop a myriad of in-
compatible systems . . . even
with the same names. For exam-
ple, I could run a Cursor program
designed for 8K memory on tape,
but if that program was designed
to use a cassette file system I’d
sure want to convert it to disk
files. I could not do that on a pro-
tected program.

What about the differences —
not trivial— between the 8K PET,
the CMC and the new 16/32K
graphics version? Although a lot
can be done to program around
these differences, I doubt that we
will be able to ever get to write a
“universal” program. I can’t.

In my mind there is no way to
handle a good utilization pro-
gram without allowing for modi-
fications for a use peculiar to the
user, and that’s what we are writ-
ing for. One solution may be a

method to protect segments of a
program while allowing modifi-
cations of those areas that need to
be customized.

Also consider for a moment
what are the potential sources of
program violation. I think that
out-and-out plagiarism is mini-
mal, and there are legal means of
dealing with this. The major
source or irritation lies with the
“make a copy for me” syndrome
between friends. This significant-
ly reduces the market for the au-
thor of the program.

I believe that this problem can
be minimized by good leadership
in the user clubs and education of
the potential users by editorials
and letters such as this. I also
think that this is the only solution
because if someone is smart
enough to protect a system, then
there is always someone else that
is just a little bit more clever who
will find a way around the block.
Micros are just too simple.

One final thought on the sub-
ject. The development of Ameri-
can literature is based upon the
examples of the past. I feel that
much the same idea applies in the
area of good programming. One
learns from concrete examples of
successful programming on the
market . The plethora of books on
beginning programming and the
dearth of any good material on
advanced programming is readily
evident. In my opinion, the wide-
spread use of protected programs
will adversely affect the quality of
our industry in the long run.

In conclusion, I think the au-
thors and publishers of programs
should consider carefully the po-
tential impact of protected pro-
grams prior to utilizing that tech-
nique. At least if one is marketing

a protected program, then he
should identify the fact so the
buyer knows what he is getting.

Paul W. Sparks
Gales Ferry CT

“Whipping” POKE

When you append two or more
programs (see Roger L. Pape’s
“Whip File Wipeouts,” July 1979,
p. 39), it may be necessary to add
the step CLEAR:RESTORE in
the command mode if your mem-
ory size disagrees with what it
should be (add this step after re-
POKEing the start of the program
pointer to its default value).

In addition, it should be noted
that the start of the program
pointer will not always be
16548,233 and 16549,66. If
TRSDOS is up, for example, it will
be 186 (LSB) and 104 (MSB).

If you use someone else’s disk
system, or some newer or older
version than 2.2, PEEK these loca-
tions without a program in the
RAM and use those values. Keep
in mind that to PEEK or POKE
above 32767 you must use the for-
mula: - 1 *(65536 -desired ad-
dress).

Robin L. Salmansohn
Abington PA

For the Birds

I personally feel we are wasting
our time and energy, especially in
printed form, for gadgets and
games whether “hard or soft.”
I’m really upset about the enor-
mous press coverage some cheap
systems, i.e., TRS-80, are get-

ting. 1 do not think a system
should become a standard just
because it has numbers. (Star-
lings, blackbirds and crows are
not national birds.) I feel the mi-
crocomputer is headed for the
“back door,” and that’s a
“10-4.” Let’s at least make this
electronic machine a little more
useful to society. Let’s start inter-
facing with the real world!

Tim Ziller
Grand Island, NB

Tim, 1 can see you ’re gonna just
love my new magazine, 80-
MICROCOMPUTING. Oh, I
agree with the need for gadgets to
permit our systems to reach out
and accomplish tasks such as lawn
watering, feeding the English spar-
rows, scratching our back, replac-
ing our aging mailman. Go take a
10-100, good buddy. — Wayne.

Greatly enjoyed “Murphy’s
Laws” (August 1979, p. 44).

Dzwonkiewicz’s maxim: Nega-
tive thinking produces negative
results. Positive thinking also
produces negative results.

Dorsey F. Burk
Rancho Murieta CA

Meet You in Philly

I am involved in trying to de-
velop, for profit, microcomputer
applications for certain areas of
the health-care industry, and I
would like to establish communi-
cations with other individuals
and organizations who are inter-

ested or involved in this particu-
lar area of microcomputer en-
deavors. Also, I am planning to
attend “Personal Computing
’79” in October in Philadelphia. I
am hoping that I might get a
chance to meet some of these peo-
ple while I’m there. In fact, I’m
proposing to get together during
that weekend in Philadelphia
such a group who, for now, I will
call Health Care Microcomputer
Entrepreneurs.

In addition to wanting to hear
from anyone who is interested in
this area of activity and who
wants to exchange correspon-
dence, I would like to receive spe-
cific indications of interest and
intent from those individuals who
would be interested in participat-
ing in such a meeting during that
weekend (October 5-7).

Thomas H. Swalenberg
HCSMS
PO Box 13089
Columbus OH 43213

OK, your letter has been pub-
lished. Now I expect you to keep
Microcomputing readers up to
date on what develops. — Wayne.

More on Mon-

Many thanks to Dave Morr for
his “TTY” program in the Au-
gust 1979 issue of Microcomput-
ing (p. 38). The program is fast,
and it makes BASIC listings very
readable thanks to the special
symbols used in the printout. For
those of you who are using a 60
wpm Baudot machine, as I am
(Teletype KSR-32), a couple of
changes that I’ve found success-
ful might be of interest.

As mentioned in the article, lo-
cation 7F93 must be changed; I
found that 24 hex was the right
value for my machine. I also
found that, apparently due to the
speed of the program, reversing
the carriage-return and line-feed
routines produced better results.
This involves changing 7EFD to
02 and 7F02 to 08. If you prefer a
64-character-wide paper printout
so that it will match the CRT of
the TRS-80, then change 7EA1 to
3F. To use the cassette motor
control relay for keying as shown
in Fig. 2 of the article, simply
change 7F88 to 14.

Before running the TRS-80 for
a hard-copy printout, make sure
that your TTY’s carriage is re-
turned and that the machine is in
the LETTERS mode. The pro-
gram does not print on the CRT
screen when talking to the TTY,
but this is very seldom needed

anyway. Again, many thanks to
Dave Morr for making available
his well-thought-out program,
and I hope that these tips may be
of value to some readers.

David F. Miller
Niles IL

I want to commend you on
your continuing publication of
excellent applications articles for
the TRS-80. An an amateur-radio
operator, I was especially pleased
with the article by David Morr on
using the Baudot teleprinter for
TRS-80 hard copy. The software
ran nicely without modification,
except that I got no automatic
CR-LF after 72 characters.

However, when I first entered
it and then typed LLIST or
LPRINT, nothing would hap-
pen. Then I discovered that the
driver addresses were not loaded
at 16422 and 16423 decimal. I
found that by adding the follow-
ing BASIC statements:

POKE 16422,176
POKE 16423,1267

the program would function
properly. Keep up the good work,
and how about some RTTY-ori-
ented Baudot input-output pro-
grams for the TRS-80?

PS. I used Rod Hallen’s
“Monitor” program from the
June 1979 issue to load Morr’s
hex listing!

A. Podolsky, M.D.

Oak Park MI

It is not Baudot code, it is Murray
code (see June 1978, p. 4). Those
confounded Frenchmen have been
taking credit for this for too long.
Murray was an American, and our
printers are and have been using
Murray code and not Baudot. Got
it? Other than that, thanks for the
additions and notes; any others
from other users of the system will
be appreciated. The whole idea of
this magazine is to allow comput-
erists to help each other — Wayne.

Lawn Care by Computer

In “Machine-Language Moni-
tors for the TRS-80” (August
1979, p. 114), author Robert Ed-
monds recommends that persons
learn 8080 code first because it is
a subset of the Z-80 code.

This is a common mistake; it
arises because Zilog engineers
wanted to preserve compatibility
with existing software. However,
the additions are not mere “en-
hancements.” They comprise a
different logical architecture that
is more elegant and efficient than
that of the 8080. Optimal Z-80
code is structurally different than

8080 code. This is primarily due
to the index registers and bit
operations; although there are
lots of registers, memory opera-
tion capability has been signifi-
cantly increased. While 8080 code
must always shove data through
the single accumulator, I find
that fewer than half of my Z-80
subroutines ever access the ac-
cumulator at all. Because I
learned 8080 first, it took me
months to learn to program that
way, but now my subroutines are
faster and only half as long.

Furthermore, “Intel standard
mnemonics” are very confusing,
and when applied to Z-80 op
codes, incomprehensible.

Come on, people, teaching
8080 code first is like teaching
people to cut their lawn with a
sickle before they can learn to use
a riding lawnmower. It’s a waste
of time.

Richard Rodman
Vienna VA

So write an article telling us how to
start writing Z-80 code, or at least
give a good reference to read on
it. — Wayne.

The Movie Was Great ....

I purchased Rodnay Zaks*
Programming the 6502 on the
basis of your review in the July
1979 issue. Your reviewer men-
tioned: “On the negative side,
Zaks’ book contains a lot of typo-
graphical errors . . . most of
them are trivial ...” This is the
understatement of the year! This
book contains not only “lots,”
meaning hundreds, of trivial
typos, but is generally illiterate in
English construction, (Example,
on page 46, “Exercise 3.1: Close
now this book.”)

However, more important is
Zaks’ lack of precise understand-
ing of the 6502. 1 thought I could
pick up some pointers on the 6502
from this book, but it is so rife
with substantial errors that you
must check every line if you really
wish to use it. For example, on
page 219 he has the code:

ADC #$00 RESTORE BIT
ROL CHAR SAVE BIT IN CHAR

After the ADC command, the
carry will be clear. The ROL will
always rotate a zero into CHAR
so the bit won’t be saved in
CHAR!

If I buy a book, I prefer it to be
mostly correct. Then I can learn
from it and not always have to be
on the defense against minor and
major errors. With this book, I

feel I was robbed! Almost any-
one, novice or not, is going to
have a hard time with it. Your re-
views should provide such warn-
ings!

Kendal T. Rogers
Fountain Valley CA

Vd like some more opinions on
this since most of the comments on
the book have been enthusiastic.
Ken, aren’t you blowing a few
minor things out of proportion?
There are some really lousy books
on the market; let’s go after these.
Readers, if you get suckered into
buying a bad book, please do write
in so we can pass the word, but be
sure you have it in perspective . —
Wayne.

Plus and Minus

Let me take this opportunity to
thank you for a great rag — one
that is well worth the air-mail
postage to New Zealand. Thank
you for the advice to jump in and
get my feet wet by buying some
kind of micro even before I fully
understood what was really going
on.

I have been a computer “pro-
fessional” for the last 11 years,
but am now learning things about
computers I never knew. It is rea-
sonably difficult to stay up with
the play at this distance, although
we have an active club here in
Auckland.

Some U.S. vendors are much
more helpful than others. I’d like
to put a plus by the names of Jade
and Personal Software, and a
minus by the names of Commo-
dore and Ohio Scientific.

Jim Kennedy
Auckland New Zealand

Thanks

Since your publication of my
letter (July 1979 Computer Clin-
ic) asking for help in obtaining
previous Popular Electronics ar-
ticles on the COSMAC Elf there
has been a tremendous response
from your readers, and I have re-
ceived all the information need-
ed, and more, on the COSMAC
Elf. Among your readers who
sent copies of the Elf articles were
Mr. Don Hartley, AR; Mr. John
Lund, IN, Ms. Joyce Weisbeck-
er, NJ; and Mr. Jeff Duntemann,
NY. I would like to thank them
for their enthusiastic help.

Moses Huang
Singapore

Food for Thought

Someday, every child will benefit from computer-assisted instruction.

Why not give your child the head start he deserves?

For the Apple*

For the TRS-80**

Math Tutor I Math Tutor II

Teacher

The Math Tutor I package is designed to
help younger children learn the concepts of
mathematics. It uses the technique of positive,
immediate reinforcement. When the child
enters a correct answer, he or she is rewarded
with the opportunity to move a spaceship, cast a
magic spell, or rescue a man from a most unfor-
tunate fate. By using this method of positive
reinforcement, children will learn to associate
mathematics with pleasant experiences, as op-
posed to the stark reality of numbers that has
driven so many pupils to an early dislike of
math. The program also provides the opportu-
nity for parents to indulge in a unique learning
experience with their children, while introduc-
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ing. Teachers can also use the program in a
classroom setting to provide that extra incen-
tive. Math Tutor I contains the following pro-
grams:

Hanging

A variation of the traditional game of Hang-
man. In Hanging, students must spare the
graphic character’s “life” by correctly answer-
ing the questions posed by the computer.

Spellbinder

The student is cast as a magician competing
against another magician who’s controlled by
the computer. He must answer the questions
about fractions correctly in order to cast magic
clouds, fireballs, and other spells at his rival.

Whole Space

The student is given the opportunity to
lead an attack on an evil planet. Every time a
correct answer is given to a math problem posed
by the computer, he can move his ship closer to
his goal. Every wrong answer gives the enemy
an opportunity to fire back.

Order No. 0073 A $7.95

Note: The Hanging and Spellbinder programs
require Applesoft II BASIC. The Whole Space
program can run in Integer BASIC.

Math Tutor II is designed to complement the
Math Tutor I package and introduces students
to more advanced mathematical principles.
Again, it uses the technique of positive rein-
forcement by offering rewards for correct
answers— a principle long recognized as effec-
tive in helping students develop healthy at-
titudes towards study. To keep pace with in-
dividual pupil’s development, all of the pro-
grams in this package may be used with any one
of four levels of difficulty. Package includes:

Car Jump

Make the car jump over the buses. Every
time your student correctly calculates the areas
of various geometric planes, the number of bus-
es in the line is increased by one.

Robot Duel

Each time a student correctly answers a
question involving volumes of geometric solids,
he’s allowed one shot at the computer “robot.”
For every incorrect answer, his shield power
drops, and the enemy robot is given the oppor-
tunity to shoot back.

Sub Attack

Students get to practice using percentages as
they maneuver their sub into the harbor. A cor-
rect answer lets them fire their torpedoes at the
enemy fleet.

Order No. 0098 A $7.95

Note: All programs in this package require Ap-
plesoft II BASIC.

•Apple and Applesoft II are trademarks of Apple Computer Inc.
••TRS-80 is a registered trademark of Tandy Corp.

See page 71 for
valuable coupon offer

As with all Instant Software programs, Math Tutor I & II and Teacher are
sold complete with detailed instructions that take even the novice step by
step, from loading and running the program, through suggestions for use
and care of cassettes.

Instant Software Inc

This practical program allows you to input
any number of questions and answers from the
Fields of science, languages, history — you name
it. Using this data, the computer will prepare
several types of tests, quiz students— providing
up to three hints per question — even offer
graphic rewards for younger children, all at the
user’s discretion. True or False tests may also be
given.

Included with the Teacher package is a
separate program, Teacher Data transfer, that
allows several tests to be recorded sequentially
on one cassette, thereby permitting the ad-
ministration of whole lessons without the in-
convenience of loading individual cassettes.
Teacher is effective, practical, easy to use —
perfect for teachers, parents, businessmen or
anyone faced with learning a lot of material in
the shortest possible time. Furnished with blank
data cassette.

Order No. 0065 R $9.95

If your local Instant Software dealer
doesn’t have the program you’re looking for,
you can order direct: Just use this order
blank or call Toll-Free 1-800-258-5473.

Name

Address

City

State Zip

□ Check □ Money order

□ VISA tJ AMEX □ Master Charge

Card No.

Expiration Date

Signed Date

Order your Instant Software today!

Quantity

Order No.

Unit Cost

Total Cost

Handling
Total Order

$1.00

Peterborough, N.H. 03458

603-924-7296

Instant Software Inc. Dept. 69J3
Peterborough, N.H. 03458 USA

Phillip Schuman
1627 Woodcutter
Wheaton IL 60187

Peter A. Stark

PO Box 209

Mt. Kisco NY 10549

Thoughts on the
SWTP Computer System

Part 6 of this series finds a coauthor, Phil Schuman. In this installment, Pete and Phil take a
close look at three of the six disks that are available for the SWTP computer system.

T here are six disk systems
available for the SWTP
system at this time— three large
floppy and three mini-floppy.
The large ones (Midwest Scien-
tific Instr., SWTP and Smoke
Signal Broadcasting) are more
expensive and quite possibly
outside the reach of many. But
the three minis are more rea-
sonably priced, and are the sub-
ject of this review. They are:

The LFD-400 from Percom
Data Company, 211 N. Kirby,
Garland TX 75042, at $600 for a
wired single-drive system or
$1000 for a wired dual-drive
system.

The BFD-68 from Smoke Sig-
nal Broadcasting, 31336 Via Co-
linas, Westlake Village CA
91361, at $800 for a single-drive
wired, $1140 for a dual-drive
system or $1480 for a triple-drive
system. A less expensive single-
drive system ($650), called the
ABFD-68, comes without case
or power supply.

The MF-68 from Southwest
Technical Products Corp., 219
W. Rhapsody, San Antonio TX
78216, at $900 kit, $1000 wired
for a two-drive system.

There are also several hybrids
among these systems. Smoke
Signal sells an MF-68-U kit,
which includes the SSB con-
troller board, to change an

SWTP MF-68 system into an
SSB-compatible system that
will run SSB software. It costs
$270. (With this kit, some drives,
a case, power supply and cable,
you could build your own SSB-
compatible system.)

Peripheral Technology Asso-
ciates, 3848 Hampton Dr., Co-
lumbus GA 31904, sells a disk
controller, model FD-1, which is
compatible with SWTP MF-68
software ($27 for a bare board,
$1 10 for a wired controller). With
this board you could change an
SSB or Percom system into one
compatible with SWTP MF-68
software. (Or, with your own
drive, case, power supply and
cable, you could build your
own.)

Likewise, Percom sells their
controller separately for $115,
wired; using this you could
modify an SSB or SWTP system
into a Percom, or build your own.

The Micro Works, PO Box
1110, Del Mar CA 92014, offers a
retrofit kit (model DM-85 at $40)
for combining 5-inch mini and
8-inch regular floppy drives on
the same SSB disk controller. It
only works with later controller
boards.

Disk System Hardware

A complete disk system con-
sists of two parts— the hard-

ware and the software. One is no
good without the other. More-
over, there has to be good soft-
ware support; the world’s best
hardware will do you no good
without a good selection of soft-
ware available. Let’s talk about
the hardware first.

Mini-floppy disk systems con-
sist of several parts. First, there
is the controller. This printed cir-
cuit board contains the elec-
tronics for controfling the disk
drives and mounts inside the
computer. The SSB and Percom
boards are large and fit into the
50-pin bus in the SWTP system,
next to memory or CPU boards.
The SWTP controller is a smaller
board that plugs into the 30-pin
I/O bus. (If your system is
already overloaded with boards
and has no empty slots in one
bus or the other, your decision is
made right here.)

Then there is the drive. All of
the commonly used drives, such
as the Shugart SA-400, Wangco
model 82, Pertec or whatever,
are exact replacements for each
other. They have the same
mounting screws, the same con-
nector and the same connec-
tions. You could mix two dif-
ferent drives in the same sys-
tem, although there are good
reasons not to do so. There are
slight differences: Some drives

allow you to flip a disk over and
use the back, some may move
the head from track to track a lit-
tle faster and some may have
more tracks.

The drive has to be mounted
in a case and connected to a
power supply. Since the con-
troller board is powered by the
mainframe, the power supply is
only for the drive or drives. It
mounts in the same case. There
are small differences here
among the three systems.

Percom’s basic one-drive
system comes in a small case
for just one drive; it has a small
supply only capable of powering
one drive. A two-drive system
has a larger case and two power
supplies. Updating from a
single-drive system to a two-
drive system either results in
two separate one-drive cases or
requires an extra charge for a
larger case.

The SWTP case comes with
two drives and a power supply
for two. (Expanding beyond two
requires a second case and
power supply.) It’s not available
with just one drive.

The SSB case and power sup-
ply are adequate for three
drives, regardless of whether
you buy the single, dual or triple
system.

Connecting the controller

30 Microcomputing, October 1979

with the drives is a cable. Most
systems use a 34-wire flat cable
with crimped-on connectors at
both ends. In multi-drive sys-
tems, one end of the cable sim-
ply has two or three connectors,
separated by about 6 inches,
which connect the same cable
to all drives at the same time.
With the exception of three
wires in the cable, which select
a particular drive, all other wires
are shared among all three
drives.

This makes the wiring simple,
but has one disadvantage:
When you read or write on one
disk, all the drive motors go on
together. This lack of indepen-
dent motor control means that
there is wear and tear on the
unused drives and disks as well.

The disk drives and the Per-
com and SSB controllers use
34-pin two-sided card-edge con-
nectors; the SWTP controller
uses an AMP 87365-4 pin-type
connector. Thus the same cable
could be used for either Percom
or SSB controllers, but another
connector has to be installed if
it is to be used on the SWTP con-
troller. (By the way, the Radio
Shack TRS-80 also uses a card-
edge connector, so the same
drives and cable could be used
on SSB, Percom and TRS-80 sys-
tems.)

Software Requirements

Along with the hardware, you
need some software. This is
where the big differences really
are among various systems. As
far as the hardware is con-
cerned, the three systems are all
differently designed and built,
but basically all work equally
well. For most people, it’s the
software that sways them from
one system to another.

Disk software consists of two
parts — the disk operating sys-
tem, or DOS, which is the entire
package of software used to
control the diskette, and the ap-
plication programs, such as a
BASIC interpreter, assembler or
editor, which are used with the
DOS.

The DOS is the essential pro-
gram that controls everything
the disk system does. It is usual-
ly broken down into three areas
of responsibility: commands,
the monitor, file management.

The commands are groups of
programs that will perform
selected functions, such as
LOAD or SAVE, for the user. A
basic set of commands is usual-
ly supplied with the system;
some additional commands
may be available at extra cost,
and the user has the option to
write his own commands in
assembly language or add other
software that will be treated as
commands.

The monitor is that portion of
the system that will maintain
control, prompt for and check
syntax of commands and inter-
face to file-management rou-
tines. The monitor is usually a
set of subroutines that may be
accessed by the user (in assem-
bly language) by way of a
jump table, with an instruction
such as JSR GETLINE or JSR
ERRMSG.

The file-management portion
is the set of routines and sup-
porting work areas that access
the diskette for reading and
writing. In addition, a directory
is maintained to ease in the
searching of the diskette for
specific files.

All of these components of
the DOS may be resident in
memory, but usually the com-
mands and other low-usage rou-
tines are kept on the diskette
and only loaded into memory as
needed.

In addition, some DOS
systems have other functions.
There is sometimes a set of rou-
tines for terminal I/O, that is, for
communicating with the ter-
minal. For example, the SWTP
DOS has its own routines for
communicating with the ter-
minal, while the SSB DOS uses
the MIKBUG or SWTBUG ROM
to perform the actual I/O.

When the computer system is
first started, there must be some
way of starting up the DOS. The
SSB and SWTP systems keep all
of the DOS on the diskette and
require a mini loader to read the
beginning portions of the DOS
into memory. Once enough of
the DOS is able to run, it loads
the rest of itself into memory.
The function of reading the be-
ginning portions of DOS into
memory is called booting, and
the mini loader program is
called the boot or bootstrap. In

the SWTP system, the disk boot
is in SWTBUG; in the SSB sys-
tem, it is in ROM on the con-
troller board; in the Percom
system, the entire DOS is in
ROM and does not have to be
booted.

Another word to learn is IPL,
or initial program load. This is
the logical sequence of bringing
a DOS up to a state of readiness.
This may involve a booting,
along with any other housekeep-
ing functions, before the system
is ready for commands.

Let’s introduce another word
that will be used later. A diskette
has a write-protect notch along
one edge. When this notch is left
uncovered, that disk is unpro-
tected and can be written on.
But when a piece of tape is
placed over the notch, the
system senses the tape and will
not write on that diskette. Hence
the diskette is write-protected—
protected from being written on.

With this introduction, let’s
look at each disk system one at
a time.

SWTP MF-68

The SWTP MF-68 consists of
a large cabinet with two drives, a
power supply, controller board,
connecting cable, a DOS and
Disk BASIC. The DOS is called
FLEX and is written for SWTP by
Technical Systems Consul-
tants, Inc. (TSC, Box 2574, W.
Lafayette IN 47906). Although
only two drives are supplied, two
more can be added with an ex-
pansion kit.

The controller plugs into port
6 of the I/O bus in the main-
frame. But it requires that a
jumper be placed across two
pins in I/O slot 5. SWTP sug-
gests that you pull out the
motherboard and solder the
jumper underneath, but a much
easier way is to simply plug a
few extra female Molex connec-
tors of the type used on the I/O
boards into slot 5 and connect
the pins on top. In any case, this
jumper uses one of the user-
defined (UD) lines on the bus
and also makes it difficult to use
port 5 for any other purpose
(since its select line is being
used by the disk). Thus the con-
troller really uses up two I/O
slots.

The controller uses the

Western Digital 1771-01 floppy
disk controller chip for disk for-
matting and is fairly uncompli-
cated, with just 13 ICs. The
1771-01 chip does all the work;
most of the other ICs are used
just for buffering inputs and out-
puts.

The bootstrap may be entered
by hand, or you may use the disk
bootstrap in SWTBUG. DOS oc-
cupies 4K of RAM at addresses
7000-7FFF; in addition, certain
FLEX commands require a large
buffer area, and, therefore, the
system also requires at least
12K of RAM starting at address
0000. This area is used fairly
seldom, however, and is other-
wise available for programs
(such as to hold the BASIC inter-
preter, for instance).

FLEX has its own sophisticat-
ed terminal I/O routines and,
therefore, does not depend on
the ROM monitor to provide this
function. This means that any
programs you write should use
the FLEX I/O routines, rather
than MIKBUG or SWTBUG I/O
routines. This is somewhat of a
problem; FLEX contains equiv-
alents of the INEEE, OUTEEE or
PDATA routines of the ROM
monitor but does not have some
of the others you might use,
such as OUT2HS or BADDR.
Hence, it may be difficult to
work your way around it.

The system uses soft-sector
diskettes, which have only one
index hole and therefore have to
be formatted before they can be
used. This is done by the DOS,
but requires several minutes for
each disk.

The FLEX disk operating sys-
tem is included in the price of
the disk system (although TSC
is now supplying a more ver-
satile DOS called FLEX 2.0 on
their own, at a price of $75).

FLEX commands reside on
the diskette. The system comes
with a basic set of commands.
Also, TSC has written additional
ones and sells them at extra
cost, and commands can also
be written by the user. Any ex-
ecutable file on the diskette may
be used as a command; FLEX
will attempt to load and start ex-
ecuting any command entered
on the terminal. The command
names, therefore, do not have
any special naming conven-

Microcomputing, October 1979 31

tions. If, for example, you enter
the word CLOAD, FLEX will look
on the diskette for a program by
that name to execute. If the pro-
gram exists, it will be loaded and
run. Hence, additional com-
mands, beyond the functions
that FLEX normally has, can be
easily added to the system.

FLEX prompts the user with
+ + + and uses control-H or
some user-defined character as
the back space. The control-X is
used to delete an entire line. A
FLEX command called TTYSET
controls these and other charac-
teristics of the terminal. For in-
stance, TTYSET controls the
line length, whether the system
echoes or does not echo char-
acters being input, and so on.
This command sets the total en-
vironment as far as the terminal
is concerned. It even keeps
track of the number of lines
printed, so that output can be
separated into pages on the
printer. A pause option allows
the output to stop at the end of a
page; hence, users with CRT ter-
minals can set up the paging
and pause so that FLEX will fill
up an entire screen with output
and then wait until the user has
read it before going on.

Since the SWTP disk system
is normally supplied with two
drives, it has provisions for us-
ing each drive for a different pur-
pose. Using the ASN, or assign,
command, you can assign one
disk as a system disk and the
other as a working disk. The sys-
tem disk will have the DOS, its
commands, BASIC interpreter,
assembler or editor, while the
working disk will have the data
files used by these programs.
This has the advantage that you
can write-protect the system
disk and protect it from acci-
dental erasure by an errant pro-
gram, while leaving the working
disk unprotected so it can be
written on.

FLEX Commands

Here is a short summary of
FLEX commands supplied with
the system. (There was an ex-
cellent review of this DOS by
Mickey Ferguson in Kilobaud,
October 1978, p. 72.) These com-
mands are referred to as the
Utility Command Set, or UCS, or
sometimes just as disk utilities.

The first two commands are
part of the DOS and sit in mem-
ory all the time:

GET— load a file into memory
and return to FLEX.

MON— return to monitor (MIK-
BUG or SWTBUG).

The remaining commands re-
side on the disk and are called
into memory only when needed:
APPEND— merge two or more
files into one.

ASN— assign system and work-
ing disk drives.

BACKUP — create a mirror-
image copy of a diskette.
BUILD— create a small text file.
CAT— list a directory of diskette
on specified drive.

COPY— copy selected files from
one disk to another.
COPYNEW— copy only those
files that do not already exist on
the second disk.

DELETE— delete a file from the
disk, erase its name from the
disk directory and free up the
space formerly used by it.
EXEC— process a text file as a
list of FLEX commands.
JUMP— start executing a pro-
gram at a specified address.
LINK— set a pointer to inform
the bootstrap program where to
find the FLEX DOS on the disk-
ette.

LIST— display the contents of a
text or BASIC file.

NEWDISK— format a blank disk-
ette with soft sectors.

P— steer the following com-
mand to use a parallel printer on
port 7 instead of the terminal.
RENAME— change name of file.
SAVE— save a specified region
of memory on the disk and op-
tionally assign it an execution
address so it can start ex-
ecuting when reloaded.
SAVE.LOW— used to save com-
mands that will be loaded into
the higher memory addresses
used by FLEX.

TTYSET— set terminal charac-
teristics and environment.
VERIFY— reread the disk after
every write to check that there
were no disk errors.

VERSION— display the version
number of a specified com-
mand.

BASIC— start the BASIC inter-
preter.

In addition, FLEX has provi-
sions for a file called

STARTUP.TXT, which can con-
tain a set of commands that will
automatically be executed as
soon as FLEX is booted. Hence,
all the assigning of terminal out-
put, system disk, working disk
or other system parameters can
be automatically done at start-
up or I PL. This is specially in-
tended for beginners or busi-
ness users who don’t want to be
concerned with the nitty-gritty
of booting the system and get-
ting it going.

FLEX Features

FLEX maintains a directory
on each disk of the files that are
stored on it. File names consist
of one to eight alphanumeric
characters (the first of which
must be a letter), followed by a
period and a three-character ex-
tension, which specifies the
kind of file it is. For instance,
commands have the extension
.CMD; text files end with .TXT;
BASIC source programs have an
extension of .BAS.

The diskette is divided into 35
tracks, and each track is further
divided into 18 sectors. One
track is reserved for the direc-
tory, with the remaining 34
tracks holding a total of 612 sec-
tors. Each sector contains 124
data bytes, for a total usable
disk capacity of 75,888 bytes.
But since the DOS has to be on
at least one disk, the first disk’s
capacity is closer to 50-60K
bytes; only the second and
following disks in a system will
generally have the full amount
usable.

Within a disk, sectors are
allocated dynamically. That is, a
given file may be spread out all
over the disk, not necessarily in
adjacent sectors. When starting
with a blank disk, a disk-for-
matting process numbers all
sectors and chains them to-
gether. That is, the directory
holds the address of the first
empty sector, that sector holds
a pointer to the next empty sec-
tor, and so on down the line.
Each sector is chained or linked
to the next one. This is called a
linked list, which links together
all the empty sectors.

While DOS is formatting the
disk, it is also checking each
sector to make sure it has no
defects and can store and read

back data without errors. Any
defective sector is automati-
cally removed from the disk
simply by not being linked in the
chain of empty sectors. In this
way, the DOS can use a disk
even if it is not perfect.

When a file is placed onto an
empty disk, it goes in the first
empty available sectors, and
then the pointer in the directory
is updated to point to the first
empty sector beyond that. As a
disk is filled up, each file goes
into the next empty sector in the
chain.

At this point, there is one
linked chain of all the empty
sectors; in the directory, there is
one pointer that points to the
first of those empty sectors.
Moreover, for each file on the
disk, there is a directory entry
that points to the first sector
used by that file. Each sector, in
turn, points to the next sector of
that file. In both cases, the chain
ends when the last pointer is
0000, indicating there is no
more.

But when a file is deleted, its
name is erased from the direc-
tory and its sectors are re-
leased, that is, their chain is
added to the chained link of
empty sectors. Now when a new
file is added to the disk, it may
start to use space that has been
released from previous dele-
tions.

In an intelligent DOS, new
files will be placed into those
areas of the disk that are big
enough to hold them, if at all
possible; in a dumber DOS, they
will simply be placed into the
first sectors in the chain of
available ones. FLEX uses the
latter technique, but either way,
often there will be no single
place big enough on the disk to
hold a new file. In that case, it
will get spread out among sec-
tors all over the disk.

This has several advantages
and disadvantages. Released
space is immediately available
to new files, rather than empty
sectors being left here and
there, unused. (For instance,
Percom’s disk doesn’t do this;
when a file is deleted on the Per-
com system, its sectors are at-
tached to the file just before it
on the disk. They cannot be
used by other files until a PACK

32 Microcomputing, October 1979

program is run to pack all the
used sectors together and close
up all the empty holes.) Since
files get spread out all over a
disk, this evens out the wear on
the disk surface, rather than
concentrating it at the begin-
ning of the disk.

On the other hand, when files
are spread out all over the disk,
more time is needed to read and
write programs. For instance, it
takes several times longer to
load a large program from the
SWTP disk than to load the
same program from the Percom
disk. Thus, it may be necessary
to reorganize a FLEX disk occa-
sionally, if just to speed up the
access time.

FLEX handles disk I/O with its
File Management System
(FMS). These routines are resi-
dent in memory, accessed via a
jump table, and provide the
necessary functions to access a
file.

BASIC and other application
programs available for use with
FLEX take care of reading and
writing disk files automatically.
But it is also possible to use the
disk for programs written in

assembly language. In this
case, all diskette I/O functions
are scheduled through a user-
created work area called a File
Control Block (FOB). An FOB is
required for each file while it is
being used. Several routines are
available in FLEX to assist the
user in properly loading the FOB
with the correct information.
Once it has been properly
primed, it must be opened for
I/O; after the I/O operations are
complete, the FOB must be
closed.

These functions are request-
ed by placing the appropriate
function code in the FOB and
calling the FMS. The FMS rou-
tines, in turn, will handle the
disk-related I/O and process a
character at a time for the user.
This is convenient for the pro-
grammer, since most non-disk
programs operate with charac-
ter-at-a-time I/O and are easily
adapted to disk for this reason.

FLEX supports normal se-
quential access, along with ran-
dom access. In addition, space
compression and other special
options are available, if re-
quested in the FOB.

However, these are all func-
tions not spelled out in the FLEX
manual that comes with the disk
system; you must purchase
DOS Advanced Programmer’s
Guide for $5 to learn how to use
them. This manual describes
how to use disk I/O for assem-
bly-language programs, but
does not give any source listing
of FLEX. Hence, you cannot go
beyond the standard techniques
as they are described in the
manual. No source listings of
FLEX or its commands are
available.

FLEX is a versatile DOS and
has an excellent collection of
related programs available for it.
The basic FLEX, which is sup-
plied with the SWTP disk system
at no charge, is called mini
FLEX, but even so it is quite a
package.

TSC is now selling several
other versions of FLEX, in-
cluding FLEX 2.0 for the SWTP
disk ($75), FLEX 2.0 for the
Smoke Signal Broadcasting
mini-disk ($90) and FLEX 1.0 for
full-size Smoke Signal disk. The
new FLEX systems require 8K of
memory from address A000

through BFFF (which means
you may have to add one or two
more memory boards), thus
releasing all of the lower 32K of
memory for user programs.
(Since FLEX is then in a new
area, old FLEX commands or
programs will have to be
changed to work with it.)

The new TSC FLEX versions
differ from mini FLEX in a num-
ber of important ways. First, the
new FLEX offers more storage
per disk. Instead of 18 sectors
per track with 124 data bytes
each, the new FLEX formats the
disk with ten sectors per track,
with each track having 252 bytes
of data. One track is reserved for
the directory, so that the remain-
ing 34 tracks hold 340 sectors,
for a total of 85,680 bytes (in-
stead of the 75,888 bytes in mini
FLEX). New FLEX disks,
therefore, have almost 13 per-
cent greater storage capacity
than mini FLEX disks, though
this becomes significant only
when each file is relatively large.
This is because a small file of,
say, 120 bytes takes up one sec-
tor in both systems; but in the
124-byte sectors of mini FLEX it

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A powerful and easy to use text editor with change, delete, insert, and
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Microcomputing, October 1979 33

wastes only four bytes, whereas
in the 252-byte sectors of the
new FLEX it wastes 132 bytes.

Since each sector contains
twice as many bytes in FLEX as
in mini FLEX, a given file will
contain only half as many sec-
tors. One reason for the slow
speed of FLEX is that after every
sector is written, FLEX waits for
the disk to turn around and then
reads the sector to make sure
there are no errors. Since the
new FLEX contains only half as
many sectors in a given file, this
process takes only half as long.
Thus the new FLEX is faster
than mini FLEX.

A major feature of the new
FLEX is printer spooling. This is
especially useful for running
BASIC programs that require ex-
tensive— and slow— computa-
tion, combined with long print-
outs. Basically, spooling takes
printer output and stores it back
on the disk as a file, at high
speed, instead of printing it. At a
later time, while running another
program whose output is also
going on disk, the first pro-
gram’s output can be printed
from the disk file at the same
time. In this way, the program
can continue running at top
speed without waiting for the
printer, while the printer can run
continuously without waiting
for the program. Essentially, two
things go on at the same time.
(The MP-T timer has to be in-
stalled in the computer to use
the spooling feature.)

There is another use for
spooling. It is possible to run a
program, store its output on
disk, and then examine that out-
put on a CRT terminal before
deciding whether to print it or
not. This avoids a waste of
paper— and time— if a pro-
gram’s results are not exactly
what is wanted.

To implement printer spool-
ing, the new FLEX has several
new commands. The 0 com-
mand is used to specify that the
output of the following program
is to go to disk with an .OUT ex-
tension. After the output is on
the disk, the PRINT command is
used to instruct FLEX to put that
program in a spooling queue to
be printed when its turn comes.
The status of programs in the
queue can be checked at any

time with a GCHEK command.
CCHEK can also be used to
delete individual files from the
queue, or an XOUT command
can delete all files that have an
.OUT extension.

Printer spooling is a tech-
nique commonly used in large
computer installations, and this
is a first in the microcomputer
area. But it also introduces
some problems. For instance, if
program output is going to a
disk, what happens if the disk
becomes full? Furthermore, if
the program whose output is go-
ing on disk also happens to be
using the same disk for files, the
running time may be appre-
ciably lengthened by the need
for the head to move from track
to track.

Since the print queue may
contain several different files to
be printed, there will often be a
need to stop the printout be-
tween files to change to a dif-
ferent kind of paper, move to the
top of a new page or make some
other adjustments. Unfortunate-
ly, FLEX doesn’t appear to have
a convenient way of inserting a
wait into its queue.

If there is a lot of printing to
be done, the disk may be on for a
long timeduring the printing; be-
cause of the design of the SWTP
controller, the motor will run
continuously during an extend-
ed print session. During an hour
of printing, the disk will make
18,000 revolutions; most disk
and drive manufacturers specify
disk life as two or three million
revolutions, but 18,000 revolu-
tions in one hour is still a large
number.

Finally, printer spooling
would be a much more valuable
feature if there were some provi-
sion for a second printer. (In-
cidentally, it is designed for a
parallel printer in port 7, not for
the terminal.)

(Percom’s INDEX DOS takes
another approach. Program out-
put can be routed to the disk, as
in the new FLEX, but its printing
at a later time cannot be over-
lapped with other processing; it
would have to be handled as a
separate job all by itself. This
provides the option of examin-
ing output before printing, but
doesn’t save the time that FLEX
does. Instead, INDEX allows the

printing to be overlapped with
the main program itself, by us-
ing a buffer area in memory and
interrupts to allow the printer to
run at the same time as the com-
puter processes data. This is an-
other approach to the problem;
FLEX may work out better in
some cases, INDEX may be bet-
ter in others.)

The new FLEX differs from
mini FLEX in several other ways.
For example, a disk is assigned
a name when it is first initialized
(though there is no mention in
the manual of the name ever be-
ing used for anything). Files can
be protected from being delet-
ed, renamed or written over,

which is an important feature. If
you want to keep a file secret,
you can also prevent it from be-
ing listed in a catalog printout.
Some other minor differences
are that some disk-resident
commands, such as BACKUP,
COPY NEW or MEMTEST, don’t
come with the new FLEX, or that
if a file is not found on one of the
drives, FLEX will look at the
other drive.

What about other software?
With mini FLEX, as part of the
system purchase price, you get
SWTP Disk BASIC Version 3.0.
This is essentially SWTP 8K
BASIC, which has been modi-
fied to work with the disk. The

Listing 1.

NAN

FLEX-TSC

EDITOR

OPT

TAP, NOG

* **************************

* * FLEX TSC/EDITOR

* **************************

* ***** FLEX-FhS FUNCTION CODES *****

0000

EQU

CALL FOR I/O

0001

READ

EQU

OPEN FOR READ

0002

URITE

EQU

OPEN FOR URITE

0004

EQU

CLOSE FILE

* ***** fcb

LAYOUT *****

0000

XFC

EQU

FCB+0 FUNCTION CODE

0001

XES

EQU

FCB+1 ERROR STATUS

0003

XUN

E0U

FCB+3 DRIVE NUMBER

0004

XFN

EQU

FCB+4-1 1 FILE NAME

oooc

XEN

EQU

FCB+1 2*14 EXTENSION NAME

0001

TXT

EQU

'TXT'' FORMAT

003B

XCH

EQU

FCB+59 COMPRESS FLAG

0000

X0N

EQU

COMPRESSION ON

00FF

X0FF

EQU

IFF

COMPRESSION OFF

♦ ***** FLEX-FNS ENTRY POINTS *****

7803

FHSCLS

EQU

17803

FMS CLOSE

7806

FMS

EQU

17806

FMS CALL

* ***** FLEX ROUTINES

*****

7103

WARNS

EQU

17103

FLEX WARM START

7115

INBUFF EQU

17115

INPUT DATA INTO LINE BUFFER

7127

GETFIL

EQU

•7127

LOAD FCB FROM LINE BUFFER

71 2D

SETEXT

EQU

171 2D

SET FILE EXTENSION

713C

RPTERR

EQU

171 3C

REPORT DISK ERRORS

7118

PSTRNG

EQU

17118

PRINT STRING END IN 104

71 1 E

PCRLF

EQU

171 IE

PRINT CR AND LINE FEED

♦ ***** OPEN FILE FOR

READ *****

1491

0RG

11491

1491

LDX

NFCB

POINT TO OUR FCB

1494

LOA

A BREAD

CODE FOR OPEN READ

1496

STA

A XFC,X

STORE FUNCTION CODE INTO

FCB

1498

JSR

FMS

CALL FLEX FMS

1 49B

BNE

ERR

BRANCH IF OPEN ERROR

1 49D

LOA

a mo

CODE FOR 1/0 PROCESSING

1 49F

STA

A XFC , X

STORE FUNCTION CODE INTO

FCB

1 4 A 1

RTS

* ***** OPEN FILE FOR

URITE *****

1 4A2

LDX

•FCB

POINT TO OUR FCB

1 4A5

LOA

A KURITE

CODE FOR OPEN URITE

1 4A7

STA

A XFC , X

STORE FUNCTION CODE INTO

FCB

1 4 A9

JSR

FMS

CALL FLEX FMS

MAC

BNE

ERR

BRANCH IF OPEN ERROR

MAE

LOA

a mo

CODE FOR I/O PROCESSING

14B0

STA

A XFC , X

STORE FUNCTION CODE INTO

FCB

MB2

RTS

* ***** ASK

TERMINAL FOR FILE NAME *****

1 4B3

ASK

JSR

PCRLF

PRINT CR AND LINE FEED

1 4B6

LDX

BASKMSG

POINT TO OUR ?? MESSAGE

1 4B9

JSR

PSTRNG

FLEX STRING OUTPUT RTN

14BC

JSR

INBUFF

INPUT RESPONSE INTO BUFFER

MBF

LDX

NFCB

POINT TO OUR FCB

1 4C2

JSR

GETFIL

LOAD FCB UITH DATA FROM BUFFER

1 4C5

BCS

SERR

BRANCH IF SYNTAX ERROR

1 4C7

LDX

NFCB

POINT TO OUR FCB

MCA

86 01

LDA

A MTXT

CODE FOR 'TXT'

14CC

JSR

SETEXT

SET EXTENSION NAME

1 4CF

RTS

1400

SERR

JSR

PCRLF

PRINT CR AND LINE FEED

MD3

LDX

NSYNTAX

POINT TO ERR MSG

1406

JSR

PSTRNG

OUTPUT SYNTAX ERR HSG

1409

BRA

ASK

GO ASK FOR IT AGAIN

* *****

» READ/URITE SUBROUTINE *****

14DB

STX

XSAVE

SAVE X-REG

14DE

STAB

BSAVE

SAVE B-ACCUM

34 Microcomputing, October 1979

SAVE, LOAD and APPEND com-
mands of BASIC allow saving
and loading BASIC programs on
the disk; cassette commands
are now TSAVE, TLOAD and
TAPPEND.

In addition, BASIC allows se-
quential data files on the disk. A
disk file is opened with an OPEN
command, which ties a BASIC
file number with a specific
named file on the disk. Subse-
quent READ, WRITE and RE-
STORE statements read or write
on the file and can reset it to the
beginning, in a sequential
fashion as if the data were going
to tape. When data is done, you
close the file. This BASIC does

not allow random files, a big
limitation to some users.

Having written FLEX, TSC is
the biggest force behind other
systems and application pro-
grams available for it. They have
an excellent text editor ($31.50
for the disk version) for prepar-
ing text and program files, an
assembler ($31.50), a text pro-
cessor ($40), a debug package
($43), a package of disk utilities
($100), a disk sort-merge pack-
age ($75) and even a super-fast
BASIC interpreter ($50), which is
claimed to be the fastest BASIC
on any 8-bit micro yet. But it only
has sequential files, not random
files.

The new FLEX 2.0 includes
the text editor, assembler, ad-
vanced programmer’s manual
and documentation as part of
the price, so that if you plan to
purchase these, the improved
FLEX package is a better deal.
On the other hand, programs
that run under mini FLEX require
changes to make them run
under the new FLEX; in some
cases major changes may be
needed. Furthermore, the new
FLEX price does not include a
BASIC interpreter; the new TSC
super-fast BASIC in the new
FLEX 2.0 form costs $55 (and in-
cludes random disk files).

Other FLEX-compatible soft-
ware is available from Com-
puterware Software Services
(830 First Street, Encinitas CA
92024) and includes a PILOT in-
terpreter, and various games
and utility programs.

Ed Smith’s Software Works
(PO Box 339, Redondo Beach
CA 90277) also has FLEX soft-
ware, including a macro-assem-
bler, disassembler, trace/debug
package and others. A PILOT in-
terpreter is also available from
SWTP.

A BASIC renumbering pro-
gram for FLEX BASIC version
3.0 is available from Lehigh
Computer Works ($10, 1132-2
Tilghman, Allentown PA 18102).

Microware Systems Corp. (PO
Box 4865, Des Moines IA 50304)
also sells mini FLEX software,
including their A/BASIC com-
piler ($150) and related inter-
preter and debugging software,
a LIST interpreter, as well as a
chess program and Eliza, a fas-
cinating computerized psychia-
trist program.

Advanced FLEX Programming
Example

An example of using FLEX
FMS and monitor routines is
shown in Listing 1 for those in-
terested in assembly-language
programming of disk opera-
tions. This listing shows the
patches to the cassette version
of TSC’s text editor, allowing it
to run under FLEX (TSC sells a
FLEX version of the Text Editor,
but this version was adapted by
Phil for users who already have
the cassette version).

The beginning of the listing
shows the entry points into the

FLEX routines used, along with
information concerning the
FCB. The next segments of soft-
ware show the open file, close
file, prompt for file name and
common I/O routines. These
new segments are added to the
editor software and referenced
by some patches to the editor
pointers. At the end of the listing
are the patches that reset the
pointers within the editor to
reflect the newly added disk
software.

A certain sequence of events
must take place to properly ac-
cess a disk file. Before the FCB
is opened, it must be loaded
with the correct information.
The proper file name, with op-
tional extension and drive
number, must be set into the
FCB. This was done using the
FLEX INBUFF routine to accept
data from the terminal, placing
it in the line buffer. The FLEX
routine GETFIL is then used to
parse the line and load the FCB
with the data that it finds in the
line buffer. The SETEXT routine
is then used to specify an exten-
sion of TXT. The file is now
capable of being opened by a
call to FMS. After the file is pro-
cessed, it must be closed by a
call to FMS.

Once the file is closed, the
FCB may be used for any I/O to
any file. In this case, only one
FCB is used for both reading
and writing of the edit buffer.

SSB DOS-68

Like the SWTP system, the
SSB system consists of a cabi-
net, power supply, controller
board, cable, a DOS called
DOS-68 and Disk File BASIC.
The cabinet and power supply
can handle up to three drives,
and the system can be bought in
one-, two- or three-drive ver-
sions.

Like the SWTP disk system,
the SSB system also uses soft-
sectored disks (though their for-
mat is not compatible, and one
system cannot read disks made
on the other). The controller also
uses the 1771-01 floppy disk
controller 1C, except that the
controller in this case is a large
board that plugs into the 50-pin
bus, like a memory or CPU
board. Hence, it does not use up
I/O slots.

14E1

LDX

4FCB

POINT TO OUR FCB

14E4

JSR

FMS

CALL FLEX FMS

1 4E7

ONE

RERR

CHECK FOR I/O ERROR. OR EOF

1 4E9

LDX

XSAVE

RESTORE X-REG

1 4EC

LDA

B BSAVE

RESTORE B-ACCUM

1 4EF

RTS

* ***** COMMON ERROR

REPORTER *****

14F0

RERR

LDA

A XES ,X

RETRIEVE ERROR CODE

14F2

CMP

A 408

CHECK FOR 'EOF CODE=08

1 4F4

BEQ

EOF

IF FOUND, EOF— ELSE ERROR

1 4F6

ERR

JSR

RPTERR

PRINT DISK ERROR CODE

14F9

JSR

FMSCLS

CLOSE ALL OPEN FILES

1 4FC

JHP

EDIT

GO BACK TO EDITOR PROGRAM

0441

EDIT

EQU

$0441

PRINT '?' AND EDITOR PROMPT

* ***** READ EOF' ROUTINE *****

1458

EQU

$1458

RETURN TO PROCESS READ

1464

EQU

$1464

EOF HAS BEEN READ

1 4FF

EOF

LDA

A KCL0SE

CODE FOR CLOSE FILE

1501

STA

A XFC,X

STORE FUNCTION CODE INTO FCB

1503

JSR

FMS

CALL FLEX FMS

1506

BME

ERR

BRANCH IF ERROR ON CLOSE

1508

LDX

XSAVE

RESTORE X-REG

1 50B

JMP

CONTINUE UITH 'EOF' PROCESSING

* ***** CONSTANTS AND TERMINAL MESSAGES *****

1 50E

FCB

RMB

192

192 BYTE BLOCK FOR OUR FCB

15CE

ASKMS6

FCC

'FILE?

1 5D6

FCB

15D7

SYNTAX

FCC

'SYNTAX

ERROR

15E3

FCB

1 5E4

BSAVE

RMB

SAVE B-ACCUM

15E5

XSAVE

RMB

SAVE X-REG

1 5E7

FCB

$00

SET BEGINNING OF EDITOR BUFFER

1 5E8

BUFFER

EQU

USER BUFFER AREA

* ***** OVERLAY OLD

CODE, AND ADD PATCHES *****

020C

0R6

$ 0 2 0 C

1/0 VECTORS

020C

JMP

READ ROUTINE

020F

JMP

URITE ROUTINE

0212

FOB

S4FFF

**** SET MEMORY LIMIT ****

0272

0RG

$0272

COMMAND TABLE

0272

FDB

$0441

'GAP' IS N0U INVALID

0358

0RG

$0358

0358

LDX

UBUFFER

POINT TO OUR NEU EDITOR BUFFER

098B

0RG

$098B

'EXIT' COMMAND

098B

JMP

UARMS

GO BACK TO FLEX

1303

0RG

$1303

'URITE' COMMAND

1303

JSR

ASK

ASK FOR OUTPUT FILE NAME

1306

JSR

OPEN FILE FOR OUTPUT

1 3D9

NOP

1 3F5

0RG

$1 3F5

PROCESS URITE EOF

1 3F5

LDX

4FCB

POINT TO OUR FCB

1 3F8

LDA

A NCL0SE

CODE FOR CLOSE FILE

1 3FA

STA

A XFC,X

STORE FUNCTION CODE INTO FCB

1 3FC

JSR

FMS

CALL FLEX FMS

1 3FF

BEQ

IF OK, RETURN

1401

JMP

ERR

ELSE REPORT ERROR

1404

RTS

1420

0RG

$1420

READ' COMMAND

1420

JSR

ASK

ASK FOR INPUT FILE NAME

1430

JSR

OPEN FILE FOR INPUT

1433

NOP

146F

0RG

$1 46F

DEVICE CONTROL

1 46F

FCB

1*1*1

3 NOP'S FOR DEVICE CONTROL

END

Microcomputing, October 1979 35

The hardware design of the
controller is quite different from
that of the SWTP controller. The
SWTP controller relies on a
bootstrap program in SWTBUG
(which does not always work
well the first time); the SSB con-
troller has the bootstrap pro-
gram and some other I/O rou-
tines in a 512-byte ROM on the
controller card; so it can also be
used with other monitors.

The controller design is in-
teresting in other ways too. In a
typical SWTP system, I/O ports 0
through 7 use the 32 addresses
from 8000 through 801 F. Ad-
dresses 8020 through 803F are
left unused for those users who
want to add a second mother-
board to provide eight more I/O
ports. But because of incom-
plete I/O address decoding, the
addresses from 8000 through
801 F are also decoded as 8040
through 805F, 8080 through
809 F and so on, all the way up
through 8FFF (or 9FFF in the
older motherboard). The SSB
controller interleaves its ROM
bootstrap and I/O routines into
the empty spaces between the
I/O ports. That is, there are 32
bytes between 8020 and 802F,
another 32 bytes from 8060
through 807F and so on, all the
way up to 83FF. This is a novel
way to sneak in some ROM into
the system without interfering in
any way with existing memory
or I/O (unless you want to ex-
pand to a second motherboard
and eight more I/O ports). The
bootstrap program starts at ad-
dress 8020, and so a simple
jump to that address boots the
disk.

The controller also uses a PIA
at addresses 9FFC-9FFF for I/O;
hence, you cannot have memory
in the 9000-9FFF area, but this is
not much of a limitation.

DOS-68 requires 4K of RAM
memory at address 7000-7FFF
but is available in optional ver-
sions that use 4K starting at ad-
dresses A000 or D000. A some-
what longer version of DOS-68
that supports random files is
also available and requires 6K of
memory at 6800-7FFF (optional
forms are available at higher ad-
dresses).

Like FLEX, DOS-68 maintains
a directory on the disk and
chains together both used and

empty sectors. File space is
allocated dynamically, and free
or available sectors are allocat-
ed as needed, so the disk need
not be repacked to combine
empty sectors (unless it is
desired to speed up the system).

DOS-68 has a set of com-
mands that are part of DOS and
always in memory and an addi-
tional set of disk-resident com-
mands (called transients) that
reside on the disk and are load-
ed into memory only as needed.
These include four memory-
resident commands:

CLOSE— close all open disk
files.

EXIT— return to the monitor.
GET— load file into memory and
return to DOS.

RUN— load file into memory and
execute it if applicable.

It also has the following disk-
resident commands:

LIST— list the directory of a
specified diskette.

SAVE— save a specified region
of memory and an optional
starting address.

GETH — load disk files created
in MIKBUG punch format (S113
. . .) from assembler or patches.
DELETE— remove an entry from
the directory and release the
space allocated to that file.
RENAME— change the name of
a file.

APPEND— combine two files in-
to one.

PRINT— display the contents of
a file.

COPY— copy a file from one
disk to another.

SDC — single-disk copy for
single-disk systems.

LINK— set a pointer to inform
the bootstrap program where
the DOS is stored on the disk.
INSTAL— rename a user file to a
command file.

REMOVE— rename a command
file into a user file.

FIND— display the starting and
ending memory addresses of a
binary program file.

VIEW— display a text file, add-
ing cursor control as needed.
FORMAT— initialize a blank
cassette.

ASYS — assign a system
diskette location.

BASIC6— start the BASIC inter-
preter.

The SSB disk system comes
with a Disk File BASIC. The in-

teresting point is that, although
Smoke Signal Broadcasting
doesn’t say so, this is Com-
puterware Software Services’
Super BASIC. It has every fea-
ture that we have gotten used to
with SWTP cassette BASICS,
plus a few new ones: a STRING
command allows the string
length to be changed; HOME
issues a home-up and erase
command for CRT terminals;
SKIP skips lines on the terminal;
WAIT inserts a time delay;
RJUST allows neater printout of
columns of figures by allowing
decimal points to be lined up.

The BASIC disk commands
include FLIST for listing the files
on the disk, FDEL for deleting a
file, FREN for renaming a file,
SAVE, LOAD and APPEND for
saving and loading programs on
the disk and CHAIN for having
one BASIC program call anoth-
er. It also supports sequential
disk files (which has caused
confusion among some readers
who thought, based on SSB
advertising, that random files
were also supported).

File commands include OPEN
and CLOSE, READ and WRITE,
RESTORE (for resetting a file

Listing 2.

NAM SSB-TSC EDITOR
OPT TAP. NOG

* *******************************

♦ * SMOKE SIGNAL TSC/EDITOR *

* *******************************

* ***** SSB-DFM FUNCTION CODES *****

0001

QS04U

EQU

OPEN FOR URITE

0002

QSURIT

EOU

WRITE DATA

0003

QSUC

EQU

CLOSE FILE FOR UNITING

0004

QS04R

EQU

OPEN FOR READ

0005

QSREAD

EQU

READ DATA

0006

QSRC

EQU

CLOSE FILE FOR READING

* ***** fcb

LAYOUT *****

0000

XFC

EQU

FCB+0 FUNCTION CODE

0001

XES

EQU

FCB+1 ERROR STATUS RETURNED TO USER

0002

XUN

EQU

FCB+2 UNIT NUMBER

0003

XFN

EOU

FCB+3 FILE NAME

0009

XEN

EQU

FCB+9 EXTENSION NAME

oooc

XFT

EQU

FCB+1 2 FILE TYPE

* ***** SSB-

-DFM ENTRY

POINTS *****

7780

0DFM

EQU

$7780

INI T OF DFM

7783

CDFM

EQU

$7783

SSB-D0S CLOSE ALL FILES

7786

DFM

EQU

$7786

SSB-DISC FILE MANAGER

7283

ZU ARMS

EQU

$7283

SSB-D0S WARM START

72B5

ZLINEI

EQU

$72B5

SSB-INPUT STRING INTO LINE BUFFER

7291

ZFLSPC

EQU

$7291

LOAD FCB FR0H LINE BUFFER

72A9

ZTYPDE

EQU

$72A9

TYPE OUT ERROR MESSAGE

* ***** MIKBUG ENTRY POINTS *****

E07E

PDATA1

EQU

$E07E

MIKBUG PRINT STRING ROUTINE

* ***** OPEN FILE FOR

READ *****

1491

0RG

$1491

1491

LDX

NFCB

POINT TO OUR FCB

1494

LDA

A NQS04R

CODE FOR OPEN SEQUENTIAL READ

1496

STA

A XFC,X

STORE FUNCTION CODE INTO FCB

1498

JSR

DFM

CALL SSB-DFM

1 49B

BNE

ERR

BRANCH IF OPEN ERROR

1 49D

LDA

A NQSREAD

CODE FOR READ SEQUENTIAL

1 49F

STA

A XFC , X

STORE FUNCTION CODE INTO FCB

1 4A1

RTS

* ***** OPEN FILE FOR

WRITE *****

1 4A2

LDX

NFCB

POINT TO OUR FCB

MAS

LDA

A NQS04U

CODE FOR OPEN SEQUENTIAL URITE

1 4A7

STA

A XFC.X

STORE FUNCTION CODE INTO FCB

1 4A9

JSR

DFM

CALL SSB-DFM

MAC

BNE

ERR

BRANCH IF OPEN ERROR

MAE

LDA

A NQSURIT

CODE FOR URITE SEQUENTIAL

14B0

STA

A XFC , X

STORE FUNCTION CODE INTO FCB

1 4B2

RTS

* ***** ASK

TERMINAL 1

FOR

FILE NAME *****

1 4B3

ASK

LDX

HASKHSG

POINT TO "NAME?" MESSAGE

MB6

JSR

PDATA1

MIKBUG OUTPUT STRING ROUTINE

1 4B9

JSR

ZLINEI

INPUT STRING INTO SSB LINE BUFFER

MBC

LDX

NFCB

POINT TO OUR FCB

14BF

JSR

ZFLSPC

LOAD FCB UITH INFO FROM LINE BUFFER

14C2

BCS

SERR

SYNTAX ERROR UAS FOUND

1 4C4

LDX

NFCB

POINT TO OUR FCB

1 4C7

LDA

A N'T

ADD 'TXT' EXTENSION

1 4C9

STA

A XEN.X

14CB

STA

A XEN+2, X

14CD

LDA

A NX

14CF

STA

A XEN+1.X

14D1

RTS

1 4D2

SERR

LDX

NSYNTAX

POINT TO ERR MSG

14DS

JSR

PDATA1

MIKBUG OUTPUT STRING ROUTINE

MD8

BRA

ASK

GO ASK GUY AGAIN

« ***** READ/URITE SUBROUTINE *****

14DA

STX

XSAVE

SAVE X-REG

MDD

STA

B BSAVE

SAVE B-ACCUM

ME0

LDX

NFCB

POINT TO OUR FCB

1 4E3

JSR

DFM

CALL SSB-DFM TO READ/URITE

1 4E6

BNE

ERR

IF ERROR. GO REPORT IT

ME8

LDX

XSAVE

RESTORE X-REG

MEB

LDA

B BSAVE

RESTORE B-ACCUM

36 Microcomputing, October 1979

back to the beginning),
SCRATCH (for erasing a data
file) and STATUS (for testing if
any errors occurred during a file
access).

SSB offers a number of other
programs for their disk system.
This includes the SE-1 Super
Editor ($29), the SA-1 Super
Assembler ($29), TP-1 Text Pro-
cessor ($40), TD-1-D Trace-
Disassembler ($26) and the SG-
1-D Source Generator ($31).
They also have a full FORTRAN
compiler ($99).

Also available are a user’s
library disk ($20) containing ad-

ditional transient commands
and an SD-2 BASIC compiler
($325). The text editor, processor
and assembler are written by
TSC and, except for the way
they use the disk and are loaded
and started, are identical to the
software available for the SWTP
MF-68 disk. The BASIC compiler
is written by Software Dynam-
ics.

Other software is available
from Ed Smith’s Software
Works; some SSB software
comes from Ed Smith’s.

Next to SSB, the most prolific
supplier of DOS-68 compatible

I4EE

RTS

* ***** COMMON ERROR

REPORTER *****

14EF

ERR

JSR

ZTYPDE

PRINT DISC ERROR CODE

14F2

JSR

CDFN

CLOSE ALL OPEN FILES

14F5

JNP

EDIT

GO BACK TO NAIN PROGRAM

* ***** INPUT 'EOF'

ROUTINE *****

1458

EQU

<1458

RETURN TO PROCESS READ

1464

EQU

<1464

READ EOF

1 4F8

1 A

EOF

CNF

A H < 1 A

TEST FOR 'EOF' CHAR

1 4FA

2 7

BE Q

EOF HAS BEEN FOUND

MFC

JNP

IF NOT, RETURN

14FF

STX

XSAVE

SAVE X-REG BUFFER POINTER

1502

LDX

• FCB

POINT TO OUR FCB

1505

L0A

A ttQSRC

CODE FOR CLOSE READ SEQUENTIAL

1507

STA

A XFC.X

STORE ITFUNCTI0N CODE INTO FCB

150?

JSR

DFH

CALL SSB-DFM

150C

BNE

ERR

150E

LDX

XSAVE

RELOAD X-REG

1511

JNP

CONTINUE UITH 'EOF' PROCESSING

♦ ***** CONSTANTS AND

TERMINAL MESSAGES *****

1514

FCB

RNB

166

166 BYTE BLOCK FOR OUR FCB

0441

EDIT

E0U

<0441

PRINT '?' AND EDIT PROMPT

1 5BA

ASKMS6

FCB

<D,<A,0,

,0,

,0,0

15C1

FCC

'FILE:

15C9

FCB

15CA

SYNTAX

FCB

<D ,<A ,0,

,0,

,0,0

15D1

FCC

'SYNTAX

ERR'

15D8

FCB

15DC

BSAVE

RMB

SAVE B-ACCUM

15DD

XSAVE

RNB

SAVE X-REG

15DF

FCB

<0D

SET BEGINNING OF BUFFER

1 5E0

BUFFER

EQU

EDIT BUFFER MARKER

* ***** OVERLAY OLD

CODE,

AND ADD PATCHES *****

020C

0RG

<020C

I/O VECTORS

020C

JNP

READ ROUTINE

020F

JNP

URITE ROUTINE

0212

FOB

MFFF

****** SET MEMORY TO BE USED

0272

0RG

<0272

COMMAND TABLE

0272

FOB

<0441

GAP IS NOU INVALID

0358

0RG

<0358

0358

LDX

•BUFFER

POINT TO BEGINNING OF USABLE MEMORY

098B

0RG

<098B

EXIT COMMAND

098B

JNP

ZUARMS

GO BACK TO SSB DOS

1 3D3

ORG

<1303

URITE COMMAND

1303

JSR

ASK

ASK FOR OUTPUT FILE NAME

1306

JSR

OPEN FILE FOR OUTPUT

1309

NOP

1 3FA

ORG

< 1 3F A

URITE EOF

UFA

LDX

NFCB

POINT TO OUR FCB

1 3FD

LDA

A MQSUC

CODE FOR CLOSE URITE SEQUENTIAL

13FF

STA

A XFC.X

STORE FUNCTION CODE INTO FCB

1401

JSR

DFN

CALL SSB-DFM

1404

BEQ

IF OK, RETURN

1406

JNP

ERR

IF NOT, REPORT ERROR

1409

RTS

1 42D

ORG

<142D

READ COMMAND

1420

JSR

ASK

ASK FOR INPUT FILE NAME

1430

JSR

OPEN FILE FOR INPUT

1433

NOP

1454

ORG

<1454

READ EOF

1454

JMP

EOF

GO TEST FOR EOF

146F

ORG

<146F

DEVICE CONTROL CHARACTERS

146F

NOP

1470

NOP

NOP OUTPUT

TURN-OFF CHAR

1471

NOP

END

software appears to be Com-
puterware Software Services.
Their Random-Access Disk File
BASIC ($90) supports not only
sequential files, but also in-
dexed sequential or true ran-
dom-access disk files, where
file entries can be changed
without rewriting the entire file.
This powerful BASIC interpreter
is faster than standard SWTP
BASICS. (There is a good chance
that this BASIC will be offered
by SSB as well during 1979.)

Computerware also offers a
Disk Check File Maintenance
system ($50), a Disk Mailing List
system, several disks with tran-
sient commands, a BASIC re-
numberer program called REN*
BAS and various other disk-
based programs.

Microware also offers SSB
versions of the same software
they offer for mini FLEX.

Advanced DOS-68 Programming
Example

Most users will probably use
the supplied software and pro-
gram mostly in BASIC, but the
system can also be used in
assembly-language programs.
The DOS-68 manual has a com-
pletely different orientation
than SWTP/TSC’s FLEX manual.
Whereas the FLEX manual is
written for the casual user and
is supplemented by an ad-
vanced programmer’s manual,
the SSB DOS-68 manual is much
more detailed and also lists the
information needed by ad-
vanced programmers.

The diskette is maintained by
a disk-file-management set of
routines. They are accessed via
a jump table that supplies entry
points for various file-handling
functions. These include open-
ing and closing files, reading,
writing and several other special
I/O requests.

Like the SWTP disk, all file
functions are channeled
through a user-created work
area called File Control Block
(FCB). An FCB is required for
each active file the user is ac-
cessing. This area acts as an in-
terface to DFM to communicate
the user’s request for I/O. The
DFM routines, in turn, use it as a
buffer to hold data, letting the
user access a character at a
time. Several routines are

available in the DOS Monitor to
assist the user in correctly
loading the FCB with the need-
ed information.

The standard DOS supports
sequential processing, and the
expanded DOS adds random ac-
cessing as well. Space compres-
sion may be requested for cer-
tain text files, along with other
special processing techniques.

An example of using the
Smoke Signal DFM routines is
shown in Listing 2. This listing
shows the patches to the cas-
sette version of the TSC Text
Editor to run on an SSB disk
system.

The beginning of the listing
shows the entry points into the
DFM routines, along with those
of MIKBUG that are used. In
addition, some offsets into the
FCB are defined for later usage.
The next segments of software
reflect the disk routines to open
a file, close a file, prompt the
user for a file name and perform
other common I/O. These newly
added segments are referenced
by some patches to the editor
code. At the end of the listing
are the patches that reset the
pointers within the editor to
reflect the new disk software.

This listing is similar to that of
the FLEX patches. There are a
few differences, mainly in the
FCB offsets and in entry point
addresses. The ZLINEI routine
is used to accept data from the
terminal and store it into the line
buffer. The monitor routine
ZFLSPC is used to parse
through the buffer and load the
FCB with the proper informa-
tion. The extension must be
loaded by hand, as there is no
routine to perform this function.
In addition, the files are stored
as memory image binary, rather
than compressed ASCII.

As you can see, though the
DOS-68 and FLEX systems are
different, they are set up in
similar ways. Thus, any soft-
ware created for one system
should be fairly easily modified
for the other.

Next month, we will examine
the features of the Percom
LFD-400 disk system and con-
clude this two-part article by
weighing the advantages and
disadvantages of each of the
three systems. ■

Microcomputing, October 1979 37

« u ■

for the APPLE II

THE PLANETS $15.95

FORMAT

PROGRAMMA'S FORMAT (Version 1.01
is a command oriented text processor de-
signed to be fully compatible with PIE
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FORMAT'S system of imbedded commands
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ation similar to text formatters found on
some mini-computers.

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FORMAT features right margin justifi-
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The following commands are available
with FORMAT:

.ad

Begin adjusting right margins

.bp

Begin page numbered n

.br

Cause a line break

.ce

Center next n lines without fill

.fi

Start filling output lines

.fo

Foot title becomes t

.he

Head title becomes t

.in

Indent n spaces from left margin

.li

Literal, next n lines are text

.11

Line length including indent is n

.Is

Set line spacing to n

.ml

Top spacing including head title

.m2

Spacing after heading title

.m3

Spacing before foot title

.m4

Bottom spacing including foot title

.na

Stop adjusting right margins

.nf

Stop filling output lines

.pi

Page length is n lines

• PP

Begin paragraphs .sp, .fi, .ti n

.sp

Space down n lines, except at top

.ti

Temporary indent of n

.ul

Underline next n input lines

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38 Microcomputing, October 1979

INNOVATIVE PRODUCTS FOR 6800 USERS

DS-68 DIGISECTOR is a random access video digit
izer featuring 256 x 256 picture element scan and
64 levels of grey scale, with conversion times as low
as 3 microseconds per pixel. It accepts either inter-
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scan conversion . . . with clever software, the Digi-
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fessional tool at a price you can afford. $169.95

B-08 2708 EPROM PROGRAMMER is a compact unit
that fits in the 6800’s I/O slot. A safety switch and
LED indicator provide control over the high pro-
gramming voltage generated on board. An industrial
quality Textool socket and extended board height
allow effortless PROM insertion and retrieval. Fully
commented source listings of U2708 is included in
the Owner’s Manual. $99.95

.it ■ Mfi

U2708 utility for testing, burning, verifying and
copying 2708s in EPROM. $29.95

PSB-08 PROM SYSTEM BOARD features IK of high
speed, low-power RAM and space for up to 8 2708
EPROMs, both DIP-switch addressable to start on
any 8K boundary in memory. The exclusive I/O
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any unused IK block in the EPROM memory space.
This permits memory expansion to a full 56K of
contiguous user RAM. $119.95

! ^D©[^r3)

is M31

DM-85 DISK MIXER is an add-on board for the
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drive-by-drive basis, so any mix of 5” and 8” drives is
allowable. The 2” x 3” PC board mounts incon-
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is completely transparent to software. An oscillo-
scope is required for the setup procedure. Kit Price:
$39.95

M6809 EMULATOR is a machine language program
that will emulate all of the functions of the Motorola
6809 third generation microprocessor. Developed
for use on any 6800 system, the program allows soft-
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Reader Service— see page 227

Microcomputing, October 1979 39

PAIA 8700 Revisited

Back in August 1979 (p. 94), Rod presented an overview of an under-200 computer, the PAIA
8700. This time, he’s going to cover a specific application for the 8700: making music.

Rod Hallen
Road Runner Ranch
PO Box 73

Tombstone AZ 85638

I n a recent article describing
the PAIA 8700 computer, Au-
gust 1979, p. 94, 1 touched on its
physical characteristics, op-
erating techniques and some

possible uses. In this article I’ll
explore one particular applica-
tion.

Computer music seems to be
a popular subject. I received
more phone calls and letters as
the result of my computer mu-
sic article (“Music, Music and
More Music,” Kilobaud, No-
vember 1978, p. 82) than any-

+ 12
CLOCK
GND [
+ 451
+426 [
+ 402 [
+ 379 [
+ 358 [

[ 2

[ 4

io h

] +478
J + 239
J + 253
1 + 268
J+284
301
+ 319
+ 338

Fig. 1. A pin-out drawing and a block diagram of the Mostek 50240
top octave generator. Inputs are + 12 volts, ground and a clock.
Outputs are 13 equally tempered semi-notes making up one octave
plus one note.

thing else I’ve ever written.
Therefore, the first thing I tried
to do with the 8700 was make
some music.

Generating Computer Music

There are two general meth-
ods of generating music with a
computer. First, the processor
can switch one of its external
leads on and off at an audio
rate. When amplified, this is
sound; if done right, it is also
music. The second way is to
use the computer to control an
electronic organ or a synthe-
sizer of some kind.

The late, great “Music Sys-
tem” from Software Technolo-
gy is an example of the first
method. It has the advantage
that it is easy to use and that no
external hardware other than
an amplifier is required. In fact,
when not much volume was
needed, I drove a small speaker
directly with TTL logic. The dis-
advantage of this method is the
limited control of the type of
sound produced. On the other
hand, using the computer to

PROGRAM PROGRAM

LEADS LEADS

Fig. 2. The block diagram of an effective music generator. The program leads could go to a switch
console or a piano-type keyboard, but the real intent is to interface them with a computer output port.

control an organ or a synthe-
sizer allows you much more
freedom of expression. After
some experimentation I de-
cided on this second method.

Since I didn’t have a synthe-
sizer, I first had to build one. I
ordered the Top Octave Experi-
menter’s kit from PAIA to use
as a starting point (seeTable 1).
I also sent for the. cassette in-
terface option kit and enough
RAM to fill up the board. The
8700 comes with 512 bytes of
RAM with space on the board
for another 512 bytes for a total
of 1024. This RAM is addressed
from 0 to 03FF hex.

I quickly installed the cas-
sette kit, which worked the first
time. A bonus of the cassette
option is a solid-state sounder
that beeps whenever a key is
touched. It also allows you to
hear the recording and play-
back of your programs. Dou-
bling RAM to IK required in-
stalling four 1C sockets and
four 2112s ICs.

The top octave kit contains a
small PC board, a 4001 CMOS
1C and a Mostek 50240 top oc-
tave generator. The latter is ac-
tually a divider that puts out 13
tones derived from a common
clock frequency. If one of the 1 3
tones is on frequency then all
of them have to be right. Using
a 2.00024 MHz clock, you can
produce the top keyboard oc-
tave.

Fig. 1 is a pin-out drawing
and block diagram of the 50240.
You can change the clock fre-

40 Microcomputing, October 1979

quency to suit your require-
ments. With a 2.00024 MHz
clock and a string of binary di-
viders any note on a piano or or-
gan keyboard can be produced.
Running these notes into vari-
ous synthesizer modules will
allow you to come up with any
sound desired.

Fig. 2 is a block diagram
showing how a piano keyboard
could be reproduced. This sim-
ple but sophisticated system is
described in “Try Computer
Composition” by Kenny Wino-
grad (July 1977 Kilobaud , p.
102 ).

Hardware

For experimentation pur-
poses I put together the simple
circuit of Fig. 3. The 4001 and
the 50240 go on the PC board
that comes with the Top Octave
Experimenter’s kit, but the rest
of the ICs must be mounted in
some other fashion. In my case
they went onto my 1C bread-
board.

Two of the gates of the 4001
(IC1) are used as an oscillator
with the 10k pot for frequency
adjustment. A frequency of
224,960 Hz fed from the oscilla-
tor to the clock input of the top
octave generator (IC2) will re-
sult in the middle octave of a
piano with A at 440 Hz. Chang-
ing the valueof Cl will movethe
range of the oscillator. A smaller
value will increase the fre-
quency and vice versa.

With Cl equal to 360 pf (two
180 pf disk capacitors in paral-
lel), the 13 semitones of the
middle keyboard octave are
present at the output leads of
the 50240. It is just a question
of feeding the desired tone to
the amplifier. The various 7400
gates (ICs 4, 5 and 6) are used to
switch one tone at a time to the
common output point. The ac-

Fig. 3. Schematic of a simple computer-controlled music generator. The TTL ICs could be replaced
with CMOS.

tual selection is determined by
the condition of the four data
leads (DO, D1, D2 and D3) from
the computer output port.

The 74154 (IC3) is a four-line-
to-16-line decoder. If the binary
code on lines A, B, C and D is
zero (see Table 2), then all out-
put lines will be high except 0. If
the binary code is 1, then all
lines except 1 will be high. Thus
it is possible to control up to 16
notes.

An inverter (ICs 8, 9 and 10) is
inverted in each output line
from the 74154 to satisfy the re-
quirements of the 7400 gates.
Since the signal we want to
pass is positive-going, it will on-
ly pass through the gate when
the control lead is also high
(see Table 3). The output of the
7400 will be inverted, but this
does not present a problem.

I used a combination of TTL
and CMOS 1C logic because
that is what I had available. You
could replace the TTL ICs with
their CMOS equivalents. This
would not only cut way down on
the current requirements but

Leads Output

LOW

L 1

Lead Value

H L

A 1 0

B 2 0

C 4 0

D 8 0

+12

Table 2. Truth table for the 74154 four-line-to-16-line decoder.
G1 and G2 must be held low at all times or all output leads will
stay high no matter what the condition of A, B, C or D is. Only
one output lead can be low at any one time. Leads A, B, C and D
are coded in binary coded decimal (BCD). The leads have the
value shown on the right. The values of all of the leads in an H
(high) condition are added together to get the equivalent deci-
mal value. For instance, if A and C are high then the decimal
value is 5.

PAIA 8700 Computer/Controller Kit

$149.95

Cassette Interface Option Kit

22.50

Power Supply Kit

24.95

Top Octave Experimenter’s Kit

14.95

Write to PAIA Electronics, Inc., PO Box 14359,
Oklahoma City OK 73114, for their complete
catalog of computer and music-synthesizer

products.

Table 1.

Lead Output

ABC
L L H

L H H

H L H

H H L

NAND Gate

SIGNAL - A

CONTROL - B

C - OUTPUT

Table 3. If the control lead (B) is held low, the output will never
change no matter what the signal lead (A) does. If the control
lead B is held high, then the output will change as the signal
does, but it will always be inverted by the 7400 NAND gate.

Microcomputing, October 1979 41

Address

Label

Op Codes

Mnemonics

Comments

0020

LOOP

20 00 FF

JSR KEYBOARD

CALL KEYBOARD SUBROUTINE

0023

B0 FB

BCC LOOP

LOOP IS NOT NEW KEY

0025

8D 20 A8

STA DISPLAY

STORE KEY IN DISPLAY

0028

4C 20 00

JMP LOOP

GET ANOTHER KEY

Program A. A 6502 assembly-language program that will cause the digital display of the 8700 to
show the key number of each key as it is pressed. Changing 20 to 40 at location 0026 will allow the
computer keyboard to control the music generator in Fig. 3.

Address

Label

Op Codes

Mnemonics

Comments

0020

LOOP

20 00 FF

JSR KEYBOARD

CALL KEYBOARD SUBROUTINE

0023

B0 02

BCC OUT

GO TO OUT IF NEW KEY

0025

A9 00

LDA NOTONE

CLEAR A REGISTER

0027

OUT

8D 40 A8

STA MUSIC

OUTPUT TO MUSIC

002A

4C 20 00

JMP LOOP

CHECK KEYBOARD AGAIN

Program B. A slight modification of Program A disables the tone when a key is not being pressed
by putting out 0 (no tone) when the keyboard subroutine returns with the carry set (no new key).

would also eliminate the need
for the + 5 volt supply since the
whole thing could run on + 12
volts.

The 7400s could be replaced
by 74C00s or 4011s, the 7404s
by 74C04S or 4069s, and the
74154 by 74C154 or 4515. You
could also use 4514 in place of
the 74154, in which case the in-
verters (ICs 8, 9 and 10) would
not be needed since the output
leads of the 4514 are already in-
verted.

The 74C00 and 4000 series
ICs are not pin-for-pin compat-
ible with their 7400 counter-
parts and are generally more
expensive than TTL. Motorola
identifies their CMOS products
with the prefix MCI. Thus the
4011 would be MC14011. Other
manufacturers prefix the de-
vice number with CD— thus
CD4011.

Without connecting Fig. 3 to
the computer, you can test the
circuit by grounding one or

more of the data leads. In fact,
for a simple piano you could re-
move the 74154 and connect its
output leads directly to a group
of switches (Fig. 4), eliminating
the computer completely. How-
ever, if this is possible why do
we even need the computer?

Yes, you can play this like a
piano with the switches in Fig.
4, but if you are not a musician,
the result may be unpleasant to
listen to. By storing the notes of
a composition in memory, you
can let the computer keep track
of the timing and play them for
you. The tempo can easily be
changed, and you can save the
music code on tape in order to
play it again another time.

The Winograd article men-
tioned previously does a good
job of covering both hardware
and software, so I won’t try to
go into too much detail here.
However, let’s see how the 8700
can be used to control the top
octave generator.

Software

The 8700 Piebug monitor (in
ROM) has a subroutine at FF00
that scans the keyboard, and
when it finds a key depressed,
it returns with the number of
the key in the A register. It also
clears the carry flag if this is a
new key since the last scan.

Program A is a simple 6502
assembly-language program
that reads the computer key-
board and sends what it sees to
the digital display. It does this
by calling the keyboard subrou-
tine, checking to see if it is a
new key, and if it is, it stores the
key number at A820 hex, which
is the address of the digital dis-
play. As you press each key, its
number appears on the display.

The parallel output port ad-
dress is A840 hex, and if we
change the 20 hex to 40 hex at
location 0026 in Program A,
then the key number will be
sent to the output port instead
of to the digital display. With
our little music board connect-
ed to the lowest four bits of the
output port, we can control the
notes from the computer key-
board.

One disadvantage of Pro-
gram A is that a note will con-
tinue to sound until a new key is
pressed because the 7800 out-
put port is a latched port that
will hold its present value until
it receives a new value. Pro-
gram B takes care of that by
shutting off the tone, except
while a key is actually being

pressed. It does this by sending
a 0 to the output port between
notes.

A 0 from the keyboard will
shut off the music since none
of the gates are connected to
the 0 lead of the 74154. Keys 1
through D will play the 13 notes
of our scale (see Table 4). This
is exactly like a piano key-
board, but as I’ve mentioned it
is better and more fun to teach
the computer to play for us.
This is accomplished by stor-
ing notes in memory and then
feeding them to the music
board along with the proper
timing for each note.

Using the techniques pre-
sented in Winograd’s article,
you can put together an inex-
pensive but sophisticated mu-
sic-generating system. The
8080 software in that article
would have to be rewritten in
6502 assembly language, but it
is a simple program and
shouldn’t present any prob-
lems.

Conclusion

These same methods could
also be used to control other
devices. In fact, anything that
can be turned on or off or ad-
justed electrically is a candi-
date for computer control,
which is what the PAIA 8700
was designed for.

Computer music is an enjoy-
able subject for software and
hardware experimentation. It
also satisfies the urge to do
something creative with your
personal computer. When
friends ask if your computer
can do anything besides play
games, it is great fun to pop in a
music cassette and let it play a
tune for them.B

Key

Note

Key

Note

NONE

Table

4. List

of the

notes

that correspond with the first

14 keys on the 8700 key-
board.

Fig. 4. A 13-note keyboard. More than one note can be played at a
time in this configuration.

42 Microcomputing, October 1979

TBS DEALERS HAVE
FULL SYSTEMS SUPPORT

You’ve just purchased
a Centronics printer.

Where do you get the
printer supplies needed to
keep it functional? You’ve
just purchased a disk drive.

Where do you find a
source of quality diskettes
and storage devices to keep
them organized? You have
invested over $ 1 ,000 in
your system. Where will
you find all the necessary
items to keep it opera-
tional? The answer: TBS
and its affiliate DEALERS.

^ The LIBRARY 100
Software Pack was pub-
lished in November of
1978. Since that time, it
has been widely accepted
throughout the United
States and 3 1 countries as
a major advancement in
microcomputer software.

Now, we at TBS have
expanded our endeavor to
better meet the product
needs of our customers.

A camera is useless

without film; a typewriter is useless without paper;
a computer system is useless without the necessary
support to make it completely operational. TBS is
leading the way in systems support, and we are
proud to announce a new concept for the micro-
computer industry - FULL SYSTEMS
SUPPORT. Mainframe and minicomputer
industries have been following this concept for
years. However, until now it has not been
available for microcomputer systems. TBS Full
Systems Support is aimed at helping you, the
computer owner, acquire the necessary support
items quickly and inexpensively through a net-
work of affiliate dealers nationwide.

We also realize that there is limited material
available on computers in general. To fill these
needs we have produced SYSTEMS EXTEN-
SIONS. This is a unique publication which pro-
vides a theoretical computer background for the
novice computer user and some specific points of
programming interest for TRS-80 users. Seven-
teen articles are included in 63 pages of solid text.

SYSTEMS ...
EXTENSIONS

Computers of the Past
Computers of the Present
Computers of the Future
Methods to Program Your System
Software Background Report
Preparation for Programming
Standards for Professional Programming Random Ramblings
Security of Business Data and Programming
Purchase. Care and Maintenance of the Business Computer

But even more important,
SYSTEMS EXTEN-
SIONS provides a source
of supply for a series of pro-
ducts applicable to all com-
puters. Through this
publication TBS and its
affiliate dealers offer over
300 items including soft-
ware, diskettes, cassettes,
printer supplies, storage
units and furniture. In
other words, TBS and its
dealers stock everything to
make the microcomputer
a full scale business system.

At the heart of your
computer system is the
software. We now offer the
following programs for the
TRS-80: TBS Business
Mail System for dual disk
and printer; Check Regis-
ter Accounting System
for dual disk and printer;
Basic Toolkit, a pro-
grammers aid; System
Doctor, a computer diag-
nostic program; Check-
book II, cassette based
personal finance; Information System, an
“in-mem” data base manager; Analysis Pad; a
columnar calculator; Terminal Control, for
RS-232 tele communications; Exerciser, for
establishing physical fitness goals and regimens;
plus, Electric Pencil; Fortran by Microsoft;
NEWDOS + ; and of course, the Library 100.
Details in full are included in SYSTEMS
EXTENSIONS.

We at TBS believe in the microcomputer revolu-
tion. Our purpose is to serve you, the microcom-
puter owner and user, by supplying the necessary
items you need. To this end we have published
SYSTEMS EXTENSIONS, and it is available
nationwide through TBS dealers and Radio Shack
Associate stores for only $3.00. For further infor-
mation please call us at the number below.

The Bottom Shelf, Inc. ^B33
P.O. Box 49104
Atlanta, Georgia 30359
Phone: 404-939-6031

Review of the Electric Pencil

The Diskette Revolution

The TRS-80 and the Business Community

Computer Aided Instruction

The Microcomputer and the Wall Socket

Level II Index

tS Reader Service— see page 227

Microcomputing, October 1979 43

An Inexpensive
TRS-80 Printer Interface

Why spend $300? Try Small System Hardware’s $49.95 alternative.

Sherman P. Wantz
424 NW Lakeview Drive
Sebring FL 33870

I f you own a “bare-bones”
TRS-80 microcomputer sys-
tem, you will eventually want to
buy Radio Shack’s $300 expan-
sion interface to provide you
with additional memory space, a
floppy disk capability, an RS-232
serial port and a parallel port to
feed a fast line printer. But sup-
pose you have a printer and
would like to connect it to your
TRS-80 but can’t see your way
clear at the moment to spend
$300?

That oversimplified scenario
described my condition before I
read the ad in Microcomputing
about Small System Hardware’s
TRS-232 printer interface unit. I
learned that for a modest invest-
ment I could give my TRS-80 a
hard-copy capability, thereby
satisfying at least a part of the
advantage I had hoped to
achieve by buying Radio
Shack’s expansion interface.

In response to the inquiry I
mailed, using Microcomputing's
Reader Service card, Small Sys-
tem Hardware sent me a bro-
chure that described its TRS-232
in detail. The brochure con-
vinced me that the TRS-232 was
what I needed to connect my
TRS-80 microcomputer to my
ASR-33 teleprinter so that I
could use my Level II BASIC’s
LUST and LPRINT commands.

Hardware

The assembled and tested
TRS-232 interface unit arrived at
my home about three weeks
after I had mailed my check for
$51.95 ($49.95 for the unit plus
$2 to cover shipping and han-
dling) to Small System Hard-
ware, PO Box 366, Newbury Park
CA 91320.

The TRS-232 consists of three
parts: a 1 x 2 x 3 inch box con-
taining a 741 op amp 1C, a tran-
sistor, five diodes, resistors and
capacitors — all mounted on a
small circuit board; a cassette
tape that contains a program
written in Level II BASIC; and a
ten-page booklet that includes
instructions, a schematic dia-
gram of the unit, a program
listing in BASIC and an assem-
bly-language source listing.

As the instruction booklet ex-
plains, the TRS-232 obtains its
signal via the gray cord that nor-
mally connects the TRS-80 com-
puter to the auxiliary jack of the
tape recorder. To use the printer,
you must remove the miniature
plug covered by a gray sleeve
from the recorder’s auxiliary
jack and plug it into either of the
two jacks that are mounted at
each end of the interface unit’s
case. The jacks are connected in
parallel so it makes no differ-
ence which one you use.

If you should want to use the
tape recorder to dump (CSAVE)
a program in memory to tape,
you must remove the miniature
gray plug from the TRS-232 jack
and reinsert it in the recorder’s

auxiliary jack.

I soon discovered that the
connect/disconnect procedure
was too easy to forget. There-
fore, I followed the manufac-
turer’s advice and built a patch
cord from audio cable, which I
terminated at both ends with
miniature plugs (Radio Shack
catalog number 274-286). I in-
stalled the patch cord per-
manently between the TRS-232
and the recorder’s auxiliary jack
(see Fig. 1) and can now print or
record programs without both-
ering to connect or disconnect
signal cords.

Power for the interface com-
ponents is obtained through a
line-cord connection that plugs
into any 115 volt wall outlet. The
TRS-232 contains no off-on
switch. It is on when it is
plugged into the wall outlet.

The line-cord plug houses a
small transformer. Current drain
through the transformer is so
small that the housing barely
feels warm to the touch.

The output signal produced
by the interface unit is fed to the
printer via a 25-pin BD-25 female
connector that is mounted
along one edge of the TRS-232’s
case.

Since the manufacturer as-
sumes that your printer is
equipped with a BD-25 male con-
nector, he provides none. I
bought the appropriate male
BD-25 connector for $2 at the
Orlando hamfest flea market.
New connectors, some com-
plete with cable, are advertised

regularly by suppliers whose
ads appear in this magazine.

Only two signal connections
had to be made to the BD-25
plug to tie the interface unit to
my teleprinter. Pin 9 provided
- 12 volts dc, and pin 10 provid-
ed + 12 volts dc. These connec-
tions supplied the 20 mA loop
current needed to operate the
ASR-33 Teletype. Consult your
teleprinter manual for appro-
priate connection points to be
made on your machine’s termi-
nal board.

The pins of the BD-25 female
socket mounted on the TRS-232
are not numbered. Fortunately,
however, those pins on the
matching male connector are
numbered; this helped me to
make the correct coupling be-
tween the interface unit and my
teleprinter.

If your printer does not re-
quire 20 mA of driving current—
as does my machine— your out-
put signal connections to the in-
terface unit will differ from
those I have just described.
Small System Hardware claims
to have used their interface unit
to drive RS-232 compatible print-
ers of all types. RS-232 is the
specification number that was
given by the Electronic In-
dustries Association to stan-
dardize voltage and impedance
levels for transmission of digital
data.

Please note that the TRS-232
interface unit provides a “re-
ceive only” one-way printer
capability, so don’t expect it to

44 Microcomputing, October 1979

permit you to use your printer’s
keyboard to send characters to
your computer.

Software

Once you have your interface
hardware installed between
your TRS-80 and your printer,
you will be ready to load
(transfer from cassette tape to
computer memory) the Level II
BASIC program that is supplied
with the TRS-232. This program
converts parallel data into serial
form to operate your printer.

When you apply power to your
Level II BASIC microcomputer,
the words “MEMORY SIZE?” ap-
pear on your video monitor’s
screen. When these words ap-
pear, you will be expected to re-
spond appropriately to reserve
memory space for the TRS-232
print function program.

If your system contains 4K
bytes of memory, you should
type “20360” to reserve space
for the 1 10 bytes required by the
program; if your machine con-
tains 16K bytes of memory, you
should type “32650.” Press the
Enter key. Now you are ready to
CLOAD the 52-line TRS-232
Level II BASIC program from
cassette tape into computer
memory.

My program loaded without
problem at a volume setting of
“4” on my CTR-33 recorder. For
those who use the CTR-41 re-
corder, the manufacturer recom-
mends a volume setting of
about “6.” After the program
has loaded, type “RUN” and
press the Enter key.

In succession, the program
will ask four questions. Your
answers to three of the ques-
tions will configure the program
to operate with your particular
printer. Your response to the
questions will: reconfirm the
amount of memory space you
reserved for the program when
you turned your system “on”;
specify the baud rate at which
your printer operates; declare
whether or not a line-feed signal
must be sent to the printer fol-
lowing each carriage return; and
specify the number of nulls your
printer requires (if any) after
each carriage return. Once you
have answered these four ques-
tions, the BASIC program

“pokes” your answers— using
machine language— into re-
served memory.

To test the operation of the
printer interface hookup, turn
your printer’s motor on, type
LLIST on your TRS-80 keyboard
and press the Enter key. You
should see the TRS-232 BASIC
program that you just loaded in-
to memory being transferred
from computer memory to your
printer.

Since the TRS-232 BASIC pro-

the design really is. The diagram
promotes the idea— whether
realistic or foolhardy— that
anyone who can read a sche-
matic should be able to trouble-
shoot and repair the interface
unit. There should be no reason
for anyone to return the Level II
BASIC initialization program
cassette to Small System Hard-
ware because he can’t load it in-
to his computer.

Since the instruction manual
contains a listing of the entire

Fig. 1. TRS-80 connections that place the interface in series between
the TRS-80 and the two output devices— printer and recorder.

gram has served its purpose
after it has “poked” your
printer’s specifications into
reserved memory space, it is no
longer needed. Type NEW to
erase it before you load the
Level II BASIC program you in-
tend using with your printer.

Documentation

In addition to containing in-
structions for connecting the
interface unit to your printer and
for using it, the ten-page booklet
that comes with the TRS-232
contains several noteworthy ex-
tras. If you are curious about
how the TRS-232 works, a sec-
tion of the instruction manual,
entitled “Theory of Operation,”
will explain it to you in simple
terms. In this section of the
manual, the manufacturer
points out that the TRS-232 is
not certified as an interface that
will meet all EIA Standard
RS-232 requirements and speci-
fications.

The schematic included with
the manual shows how simple

program (52 lines long— includ-
ing 16 REMark lines that need
not be used), it would be far
simpler to type the program into
memory using the computer’s
keyboard and then CSAVE it us-
ing your own computer, recorder
and cassette tape. Because of
slight record-head-alignment
differences that exist among
tape recorders, it is almost
always easier to CLOAD tapes
made on your own recorder than
it is to load from tapes recorded
on other machines.

Having the Level II BASIC
listing in your instruction
manual gives you peace of
mind, too. Even if you do in-
advertently store your ini-
tialization program cassette
next to your TRS-80 system’s
power supply and partially erase
it, you can always regain the use
of your interface unit by typing
and rerecording the program.

The instruction manual con-
tains a special bonus for those
who do their programming in
Z-80 machine language. A com-

plete listing in assembly lan-
guage and machine code of the
relocatable driver for the
TRS-232 is provided. The code
can be placed anywhere in mem-
ory since no calls and only rela-
tive jumps are used.

Baud rate selection (110 to
9600), line feed and nulls follow-
ing carriage return options are
provided, just as they are in the
Level II BASIC program. There-
fore, with the TRS-232 interface,
you can obtain a print capability
with your machine-language
programs as well as with those
that are written in Level II
BASIC.

Conclusion

If you have a printer that you
want to use with your TRS-80
system, you could hardly ask for
a more reliable unit to tie com-
puter and printer together than
the TRS-232. Small System
Hardware claims to have used
the TRS-232 to interface with
Diablo, Texas Instruments, Cen-
tronics, Teletype and Selectric
printers.

Since the TRS-232 is not a kit
—it comes fully assembled and
tested— you will need no spe-
cial skill, beyond the ability to
follow written instructions, to in-
stall it in series with your TRS-80
microcomputer’s output cable
(the gray cord that terminates in
a miniature plug enclosed in a
gray plastic sleeve).

When you inspect the
TRS-232 hardware housed in the
1 x 2 x 3 inch box, you may feel
that the $49.95 price you paid for
the unit is a bit steep. The price
was $39.95 in December 1978
and jumped $10 at the beginning
of 1979. However, when you re-
member that your purchase
price also paid for a software
package that will allow the
same hardware unit to connect
your TRS-80 to the next serial
printer you acquire, the price
doesn’t seem too far out of line.

I am quite pleased with the
hardware, software and instruc-
tion manual that comprise my
TRS-232 interface. For my $50
interface investment, I obtained
the use of a teleprinter that cost
at least ten times that much.
Particularly for a computer hob-
byist, that’s not a bad invest-
ment ratio. ■

Microcomputing, October 1979 45

Jerry Sorrels
6266 Banner Ct.
Riverside CA

Eyes for the AC-30

A simple modification lets you add monitoring features to your AC-30 cassette interface.

F or over a year I had been
using a Bit Boffer (see
“Build a Bit Boffer,” Byte,
March 1976) to load programs
into my SWTP 6800 computer. It
worked just fine but lacked the
ability to change from play to
record and to start and stop the
recorder under software con-
trol.

At first this was no problem
... I had enough on my hands
just getting the programs
loaded and working. But as
time went on, I became smarter
and lazier.

Enter the SWTP AC-30 audio
cassette interface. After using
it for a short time, I missed one
of the features of my old Bit
Boffer: the ability to display the
data on my SWTP CT-1024 ter-
minal at the same time it was be-
ing loaded into the computer.
This feature lets you verify if
the tape is being read properly.
Also, you know when the end is
nearing.

But its best feature is that it
gives you something to look at
while waiting for the program
to load. 300 baud is just a little
slow!

After looking over the SWTP
19 x 25 inch schematic (nice
and big), I came up with a simple
way to add this monitoring fea-
ture to the AC-30. The only parts

I used were an SPST toggle
switch and a Ik resistor (see
Fig. 1).

How It’s Done

To add this modification to
your AC-30, remove the circuit
board from the case. Next, on
top of the board, cut the trace
between pins 10 and 11 of IC1 4
— it will be under the 1C or its
socket. I discovered that on the
type of sockets I used (I always
use sockets) the plastic hous-
ing could be pried off the pins

and replaced after cutting the
trace. What luck!

Now, on the bottom of the
board connect a wire from IC14,
pin 11 to an unused pin on the
rear center board connector;
next on the bottom, solder a Ik
resistor, R1, from IC14, pin 11 to
IC14, pin 16, which is +5 volts.
Connect one side of the switch
to the male pin that matches
the vacant board connector you
used. The other side of the
switch connects to the pin that
matches the rear center con-

MONITOR

Fig. 1. Section of AC-30 cassette-tape-switching schematic
showing modification.

nector labeled LOCAL/REMOTE
on the placement diagram.

I mounted the switch at the
right rear of the cabinet, out of
sight but still accessible. I have
since considered moving the
power switch to the back and
the monitor switch to the front
because sometimes I forget to
put it in the normal position and
wonder why the computer is
not speaking to me.

When you want to monitor a
tape you are loading, place the
switch in its open position. This
will change data selector IC14c
from the computer to the cas-
sette demodulator output. This
causes the data to be sent to
the computer and to the termi-
nal. When the switch is in its
normal position (closed), the
AC-30 operates normally. This
modification is especially use-
ful when you’re loading some-
one’s tape other than your own
for the first time without having
to check its readability in the
LOCAL mode first.

If the computer receives bad
data during a normal load, it
will send question marks to the
terminal. Remember: With the
switch in the monitor position,
the terminal is looking at the
AC-30, not the computer; but if
there is bad data, the TVT
should show it anyway. ■

46 Microcomputing, October 1979

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Microcomputing, October 1979 47

Expanded

TRS-80 Disk Operations

Putting “system” programs on disk is the topic in this, the first of a two-part series.

Allan J. Domuret
7825 Willowcrest Way
Fair Oaks CA 95628

T his article has two objec-
tives. One is to explain how
to put low-RAM machine-lan-
guage programs on disk, a pro-
cedure that is not routinely sup-
ported by the Radio Shack disk
operating system (DOS). Sec-
ond, the techniques described
herein will serve as a good in-
troduction to machine-language
programming for beginners.

The techniques make use of
the Small System Software
RSM2 or RSM2D machine-lan-
guage utility program. RSM2
has many features, and only a
few are described herein. If the
user does not have RSM2 in his
software library, this article
can still be educational. It is
suggested, however, that RSM2
or RSM2D is an invaluable utili-
ty for TRS-80 owners. RSM2D is
the disk version of RSM2.

TRS-80 Disk Operations

The comparatively low price
of the TRS-80 microcomputer,
no doubt, contributes consider-
ably to its popularity, but, as an
old philosopher once said,
“You get what you pay for.” It
seems that whenever a TRS-80
user updates or adds to his sys-
tem, he encounters some kind
of new frustration. What I refer
to is a deficiency in Radio
Shack’s DOS, which precludes
loading system programs such
as the Electric Pencil, EDTASM

or T-BUG from disk because
these programs reside in the
same memory area as does
DOS.

To quote from the new Radio
Shack “Disk Operating Sys-
tem” manual for TRSDOS Ver-
sion 2.0: “Most Radio Shack
system tapes designed for use
with Level II TRS-80s will not
work under Disk BASIC be-
cause of differences in RAM us-
age under Disk BASIC and Lev-
el II” (pp. 5-6). On the same
page of the DOS manual is a
comment that states, “Do not
attempt to use Tapedisk to load
tape files that load below hexa-
decimal address 54F4 (decimal
21748). Tapedisk uses this
area.” (Tapedisk is a utility pro-
gram that allows the user to
place system tapes on disk,
provided that memory required
by the system program does
not overlap that required by
Tapedisk or DOS.) In other
words, it is not possible (nor-
mally) to put a machine-lan-
guage program on dfsk if the
program conflicts with DOS in
low RAM.

This means that the inexperi-
enced TRS-80 user cannot easi-
ly put system programs such as
T-BUG, Electric Pencil or Editor/
Assembler on disk with avail-
able routines such asTapedisk.
With a little skill and cunning,
however, it is possible to load
these low-RAM system pro-
grams from disk, thereby elim-
inating the need for much
slower tape loading.

The technique involves load-
ing the desired system program

into upper, unused memory with
RSM2. Then a short block-move
subroutine (15 bytes) is perma-
nently attached to the system
program to automatically move
the entire system program to
its proper memory location for
execution. Finally, the Tape-
disk routine is used to put the
program and its block-move
subroutine onto disk.

Subsequently, when the pro-
gram is loaded from disk, it is
loaded into upper memory with
an execution address that initi-
ates the block move. The block
move takes over and transfers
the program to its proper mem-
ory location. When the block
move is completed, a jump to
the program’s execution ad-
dress completes the operation.
The program will then run nor-
mally.

Moving the system program
to lower RAM in this way over-
writes DOS because DOS re-
sides in the same memory loca-
tion as the moved system pro-
gram. But this is inconsequen-
tial because only the system
program will be run— DOS will
not be needed while the system
program is running. For ex-
ample, DOS and the Electric
Pencil normally reside in the
same memory area, but only
one program will be used at a
time. Wiping out DOS by over-
writing it with the Electric Pen-
cil does nothing to interfere
with normal Pencil operations.

The “Save-to-Disk” technique
described in this article will use
the Electric Pencil as an exam-
ple, but the reader, if he under-

stands what is happening in
this simple routine, can apply
the same technique to other
system programs such as
T-BUG, Radio Shack’s Editor/
Assembler, and so on.

The recent release of a disk
version of the Electric Pencil
for the TRS-80 will not obviate
the relevance of the procedures
described in this article. The
technique is still applicable to
any system program, and, no
doubt, there are those who may
not be able to afford the new
disk version of the Pencil.

Also, the ability to load the
Editor/Assembler from disk
eliminates much of the
drudgery from machine-lan-
guage programming. It only
takes a moment for your ma-
chine-language program to
crash, but it takes many frus-
trating minutes to reload the
EDTASM and the source mod-
ule for making repairs.

Part 2 of this article will ex-
plain howto put Peter Jenning’s
Microchess 1.5 on disk and
also how to make backup
copies on cassette tape. As
most TRS-80 users have be-
come aware, Microchess 1.5
cannot be duplicated on cas-
sette tape by ordinary means.
You paid good money, however,
to purchase Microchess, and
we all know the importance of
having backups of valuable pro-
grams. It is also an educational
experience to learn how to du-
plicate Microchess. I can only
encourage TRS-80 users not to
abuse this knowledge by mak-
ing free copies for friends.

48 Microcomputing, October 1979

(Sorry, Mr. Jennings, but knowl-
edge must be shared.)

RSM2 and RSM2D
System Monitor

As I stated, RSM2 and RSM2D
will be used as a tool to accom-
plish our purpose. The only dif-
ference between RSM2 and
RSM2D is that the latter has
some disk-related features.
These disk features are not re-
quired for the techniques em-
ployed in this article, so they
will not be referred to again.
Subsequent references to
RSM2 apply as well to RSM2D.

RSM2 has several tape-relat-
ed features that enable the user
to read and write system tapes
and to read virtually any ma-
chine-language tape into mem-
ory (including Microchess).
These tape features are neces-
sary for structuring system pro-
grams that will eventually be
saved on disk.

Before proceeding, I should
mention that either the 32K or
48 K version of RSM2 is prefer-
able to working with the 16K
version. If you must work with
the 16K version because of lim-
ited memory availability, it will
be necessary for you to deter-
mine your own memory-address
requirements as described in
this article.

Using the 32K or 48K version
of RSM2 should present no
problems because most TRS-80
users quickly learn that a 16K
system with DOS is really not
enough. Consequently, they
usually move up to 32K or 48K
of memory rather quickly. Those
of you who will be using the 32K
or 48K RSM2 can use the pro-
gram address numbers exactly
as provided in the following
paragraphs.

The first step in creating our
disk file is to determine the
start, end and execution ad-
dresses of the selected system
program. As was stated above,
we will use the Electric Pencil
for our example. To determine
these addresses, load either the
32 K or 48 K version of RSM2 as
you would any typical system
program.

If you are still limited to a 16K
TRS-80, it will be necessary to
work in BASIC II rather than in
Disk BASIC. The reason is that

Disk BASIC occupies memory
space that, when added to mem-
ory space used by RSM2, leaves
an insufficient amount of mem-
ory for our operations on the
Pencil program. In spite of limi-
tations imposed by 16K sys-
tems, the techniques described
herein will still work for loading
Pencil from disk.

After RSM2 is operational, it
would be a good idea to clean up
all memory locations to avoid
confusion later when working
on the Pencil. Before loading
Pencil into memory, zero out all
memory locations from 4200 hex
to a place in memory just short
of running into RSM2. For a 16K
TRS-80, RSM2 resides at 6C00 to
7EFF hex (see “Supplementary
Information” provided with
RSM2 documentation). The
command for a 16K system
would be: “Z 4200 6BFF.” For
the other RSM2 versions, zero-
ing memory from 4200 to, say,
8000 will be adequate for our
purposes.

Now when we load in the Pen-
cil program, there will be noth-
ing else in lower RAM to confuse
us as to which instructions
belong to Pencil and what might
otherwise be hanging around as
leftovers from DOS or some
other program that is no longer
needed. The only memory loca-
tions that will not be zeroed will
be the Pencil program, which we
will load.

Prepare the cassette recorder
and read in Pencil with the
RSM2 “R0” command. When
the Pencil is loaded, RSM2 will
display the file name— PENCIL
—and it will also display the ex-
ecution address. For Pencil, the
execution address will be 4350
hex. Write down the execution
address for later use.

By the way, in case you won-
dered, the Pencil execution ad-
dress is physically located at
the end of the cassette tape pro-
gram, and this holds true for
most system programs. This is
how the TRS-80 knows where to
go to execute a system program
when you enter the slash (/) after
normal tape loading, and this is
how RSM2 is able to tell you
what the execution address is.

If you want to check this out,
read the Pencil into memory
with the RSM2 “R” command (in

contrast to the R 0 command).
The R command will load in the
program and will display the ex-
ecution address at the end of
the program. The R command is
used for reading in non-system
programs, but will read in sys-
tem programs with all coding
characters preserved in mem-
ory. The execution address for a
system program will follow the
termination code “78” at the
end of the tape.

After loading Pencil with the
RSM2 R0 (not R) command,
Pencil should be in its normal
memory location, but RSM2 will
still be in command of the ma-
chine. To determine Pencil's
start and end addresses, use
either the RSM2 ASCII or sym-
bolic dump commands. The
ASCII dump is faster for locat-
ing the Pencil in memory, but
the symbolic dump is more pre-
cise in determining exact start
and end addresses.

To get an ASCII dump, answer
RSM2’s “COMMAND?” prompt
with: “A 4300.” This will give a
scrolling ASCII display of every-
thing in memory starting from
memory location 4300 hex. Stop
the scroll as desired with the
space bar. Since we initially
zeroed ail memory locations be-
fore starting, and since RSM2
resides in higher memory, we
can be certain that the first
nonzero data encountered dur-
ing the ASCII or symbolic dump
belongs to the Pencil that we
loaded in with RSM2.

Since the ASCII dump makes
it difficult to precisely read pro-
gram addresses, the exact start
address for the Pencil can be
determined with the RSM2 sym-
bolic dump. Start the symbolic
dump at, say, 4300 hex by typing
in: “S 4300.” Notice that adja-
cent to the displayed memory
locations between 4300 and
434 F are zeros (00) and NOPs.
This is because we zeroed all
memory before loading in the
Pencil. When the dump reaches
4350 hex, the start address for
the Pencil, you will see:

4350:C3 DA 52 JP 52DA

followed by the rest of the pro-
gram in Zilog mnemonics.

The first column (4350) is the
hex memory location of the first
instruction in the program; the
second column group (C3 DA 52)

represents the hex op codes,
which tell the computer what to
do; and the next column group
(JP 52 DA) represents the sym-
bolic code to JUMP to memory
location 52DA hex.

To find the end address, just
let the memory scroll continue
until a long string of zeros is
again encountered. By now, the
importance of zeroing all un-
used memory as we did at the
start should be obvious. The last
instruction in the Pencil pro-
gram should read:

5365: 29 ADD HL.HL

The end address is 5365, and
the 29, rather than representing
a machine-language op code, is
actually an ASCII character for
“)". An “ADD HL,HL” sym-
bolic instruction is displayed
because the RSM2 disassem-
bler interprets the 29 op code as
an “ADD HL,HL” instruction.
RSM2 really has no way of tell-
ing if the 29 is an ASCII char-
acter or an op code without ac-
tually running the Pencil pro-
gram.

This is a common fault for
most disassemblers, and the
user should always be aware of
this problem so that ASCII char-
acters are not inadvertently in-
terpreted as op codes. ASCII
characters can be found easily
with RSM2 by dumping memory
with the ASCII dump command
and finding the English lan-
guage text in the program. For
Pencil, this English language
text is found in upper memory.

At this point, I must add that
Pencil is recorded on the cas-
sette tape with ten trailing zeros
after the last code, 29. 1 learned
this by loading Pencil into mem-
ory with the RSM2 R command,
in contrast to the R 0 command.
The R command will read vir-
tually any tape, whereas the R 0
command is for reading only
system tapes.

If you care to experiment,
read in Pencil using the RSM2 R
command, and at the end of the
program you will find the ten
trailing zeros, followed by a few
other characters, Including the
78’ termination code and, at the
end, the execution address as I
mentioned above. Little peculi-
arities like these must be found
when manipulating programs at
the machine-language level. At

Microcomputing, October 1979 49

this point, we will keep in mind
these ten trailing zeros and ac-
count for them later.

After copying down the start
and end addresses, you should
have available all the informa-
tion you need to continue: the
start address, the end address,
the execution address and the
file name, PENCIL

Figuring Program Length

Since we now have the neces-
sary start, end and execute
memory address information for
Pencil, we must compute the
program length. This is needed
in order to determine how much
memory is eventually to be
block-moved and how much
memory is to be transferred to
disk. Simply subtract 4350 hex
(the start address) from 5365 hex
(the end address).

It is not my intention to give
instructions here on how to do
arithmetic in hex . . . there is
plenty of source material avail-
able for that. Very briefly, how-
ever, it is not much different
than doing adds and subtracts
in the decimal system, the only
difference being that when bor-
rows or carries are done, we bor-
row or carry 16 for a hex problem
rather than 10 as in a decimal
problem. In our subtraction
problem for the Pencil, there is
no borrow needed.

5365

4350

1015

Observe that this works out
just as if it were an ordinary
decimal subtraction problem
because no carries are involved.
As another example, suppose
that we needed to subtract 4359
hex from 5365 hex.

5365 ) 5 3 5 21

)

4359 ) Becomes 4 3 5 9

)

100C ) 1 0 0 12

(or 100C hex)

Nine cannot be subtracted
from 5, so we borrow a one from
the 6 in the numerator. This bor-
rowed 1 from the second digit is
actually a 16 in the least signifi-
cant digit. It is necessary to add
this borrowed 16 to the least sig-
nificant digit (5) for a total of 21.
Now subtract 9 from 21 and get
12. Twelve is represented in hex
by a C; hence the C is the least

significant digit in our answer.
The rest of the subtraction is
completed without any addi-
tional requirement for borrow-
ing.

Of course, you can always
take the easy way out and let
RSM2 do the hex arithmetic for
you. Simply type in the two hex
numbers with the appropriate
command, and RSM2 will give
the sum and difference for the
two hex numbers in both hex
and decimal notation (see page
4 of the RSM2 documentation).
The command for this binary
arithmetic is:

B 5365 4350

RSM2 will return with both the
hex sum and difference for
these two numbers: 96B5 and
1015 hex, respectively.

Getting back to our Pencil
problem, we subtracted 4350
hex from 5365 hex for a differ-
ence of 1015, but determining
the true program length requires
that we add 1 to 1015 for a pro-
gram length of 1016. The reason
for this can best be explained
with an example.

Suppose we had a trivial ma-
chine-language program resid-
ing in memory locations 1
through 5 inclusive. But sub-
tracting 1 from 5 only gives us 4,
whereas we know that the pro-
gram actually occupies five
memory locations. It is neces-
sary, therefore, to always add 1
to the arithmetical difference
between the start and end ad-
dresses when we want to deter-
mine the exact program length.
We conclude that our Pencil pro-
gram is 1016 hex bytes long. (For
informational purposes only,
that figures out to be 41 18 bytes
in decimal.) Write down the hex
program length for later use.
(No, I haven’t forgotten the ten
trailing zeros. I will get to them
eventually.)

Relocating Programs in Memory
with Block Moves

We now know that Pencil
starts at memory location 4350
hex and up, and we should also
hazard the guess that DOS and
most TRS-80 disk routines over-
.lap this same low-RAM memory
area. To reiterate, the trick we
hope to accomplish is to have
DOS load Pencil from disk into a
higher area of unused memory

where the two don’t overlap;
then when Pencil is safely in an
unused area of memory, we
want it to automatically move
itself to a start address of 4350
hex after DOS is no longer need-
ed. Actually, this is simple to do.

Eventually, we are going to
use the Tapedisk utility to put
Pencil on disk. But first, recall
the warning from the TRSDOS
manual: “Do not attempt to use
Tapedisk to load tape files
which load below hexadecimal

address 54F4 ” If we can get

Pencil to initially load from disk
to a higher memory location
than 54F4, we should be in good
shape.

Actually, I have found through
trial and error that it is better
still to load the Pencil program
from disk into memory above
6000 hex. If the Pencil is set up
to load at, say, 5500 hex, DOS
sometimes does funny things
because this area of memory is
the DOS “overlay area.” Play
around with this by utilizing
memory starting at 5500 hex,
rather than 6500 hex, as will be
described below, and see what
happens.

My TRS-80 will run the pro-
gram but will not load it. You
can’t hurt anything if yourdisk is
write-protected and if you keep
a backup copy of the program
you are working with. For our
purposes, it works fine if mem-
ory locations 6500 hex and up
are used for the Pencil. Take my
word that this will eliminate
some unexpected problems.
Those of you confined to a 16K
memory will have to use 5500
rather than 6500 for your work-
ing memory address as de-
scribed below.

If DOS can load Pencil to
memory location 6500 hex, DOS
will have done its job and will no
longer be needed, and Pencil

can subsequently be moved to
its proper focation at 4350 hex.
So let’s move Pencil from where
it was initially loaded at 4350
hex to memory location 6500
hex, using RSM2. The RSM2
command which will accom-
plish this move is:

M 4350 5365 6500

This command says: “Move
data (i.e., the program) residing
between memory locations 4350
and 5365 hex inclusive and
move the whole thing to a
destination address starting at
6500.”

After you have performed this
operation, use the RSM2 ASCII
or symbolic dump to verify that

Pencil has indeed been relocat-
ed. With the symbolic dump
command, you will find Pencil’s
first instruction— JP 52DA
—residing at memory location
6500 hex, exactly where you
moved It to. You can also verify
that the original Pencil, which
was initially loaded at 4350, is
still there, but you can ignore it
now because we will no longer
need it.

The next step is to put the
15-byte block-move routine on
the tail end of the relocated Pen-
cil, which is currently residing at
memory location 6500 hex and
up, so that Pencil will automati-
cally load itself into its proper
memory location at 4350 hex
after DOS is no longer needed.
Refer to the block-move instruc-
tions in Table 1.

There are several important
points to note in Table 1. First,
the block-move instruction is
put into unused memory start-
ing at 7520 hex. This* unused
memory is at the tail end of Pen-
cil and allows for the ten trailing
zeros that were mentioned
earlier. The relocated Pencil
should be residing at 6500 to
7515 hex inclusive; and the last

Memory Op Code Mnemonic Comments

7520

;Disable Interrupt

7521

21 00 65

HL.6500

;Source Address

7524

11 50 43

DE.4350

;Destination Adrs

7527

01 20 10

BC.1020

;Byte Count

752A

ED B0

LDIR

;Block Move Inst

752C

752F

C3 50 43
FF

4350

;JP To Execute Adrs

Table 1. Block-move instructions.

50 Microcomputing, October 1979

memory location at 7515 should
read “7515: 29 ADD HL,HL,”
just as it did in the originally
loaded Pencil, except for the
7515 address. Then we skip
down to memory location 7520
for inserting the block-move in-
structions. This allows for the
trailing zeros.

Second, when we are fin-
ished, this block-move routine
and the trailing zeros will be-
come permanently attached to
the tail end of the Pencil pro-
gram. After explaining what the
block move does, we will go
ahead and program it in with
RSM2.

The first instruction— Dl —
means “disable interrupts.” Its
purpose is simple, but impor-
tant: We don’t want any inter-
rupts interfering with the block
move while it is being accom-
plished by the Z-80 CPU. What
we are actually doing is turning
off the real-time clock in the
computer so that it will not tick
in the midst of the block move
and mess things up. (This is
what you do when you type
“CMD T” before loading or sav-
ing a cassette tape. You are
turning off the real-time clock so
that it does not interrupt tape
operations.) The machine-lan-
guage op code that disables in-
terrupts is F3.

The next instruction — LD
BC, 1020— is the byte count
loaded into the BC register. Re-
member, we computed this byte
count earlier, but this time we
are accounting for the trailing
zeros. We will be moving 1020
hex bytes. The op codes for
“load BC with something” is 01,
and BC is loaded with 1020 hex.

Note: In the op-code column
the 1020 hex byte count appears
to be reversed when reading
from left to right. Rather than
reading “01 10 20,” it says “01 20
10”— the 20 and 10 are reversed!
This is normal and occurs be-
cause the CPU works sequen-
tially; after it gets the “LD BC”
instruction (01), it next looks for
the least significant byte, which,
in our case, is the 20. Next, the
CPU looks for the most signifi-
cant byte, which is 10.

Be aware of this convention
to avoid future problems in ma-
chine-language programming!
The Zilog mnemonic reads ac-

cording to English language
convention because it says LD
BC,1020, which is how it would
be actually programmed if you
were programming in assembly
language with the Editor/As-
sembler. But the machine-lan-
guage instruction appears to be
reversed. We will be program-
ming in machine language, not
assembly language, with RSM2.

The next instruction says to
load 4350 into the DE register.
This is the destination address
for the block move that we will
be programming in; it is where
Pencil has to be moved to after
DOS initially loads it to memory
location 6500 hex. The machine-
language op code is “11 50 43.”
Note again that the 4350
destination address in the op
code reads backwards as 50 43.

The next instruction is the
source address (6500) where the
first Pencil instruction is resid-
ing. It is where the block move
will be initiated when it starts to
relocate Pencil from 6500+ to
4350 + hex. The source address
is loaded into the HL register,
and the machine-language op
code is “21 00 65.” The 6500 ad-
dress is again reversed to 00 65
in the op code.

The LDIR instruction is the
biggie; it accomplishes the en-
tire move using the information
stored in the BC, DE and HL reg-
isters. Here is how it works:

1. Get the first byte contained
in the memory location refer-
enced by the HL register— 6500,
in our case. This is the source
address.

2. Move this byte (i.e., C3 op
code) to the destination address
referenced in the DE register-
4350, in our case.

3. Decrement the byte count
in the BC register. Increment the
HL register and get the next
byte. Increment the DE register
and load this next byte to the
new address referenced by DE.

4. Repeat step 3 until the BC
register reads zero. Thus, the
whole program will be moved.

Note that the block-move rou-
tine forms a loop. The CPU will
continue within the block-move
loop until the byte count in the
BC register is zeroed. After the
move has been completed, there
is one more instruction: “JP
4350.” This jump is to the execu-

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Microcomputing, October 1979 51

tion address for Pencil. After
this jump, Pencil will start.

Before proceeding with in-
structions on how to get the
Pencil and its block-move pro-
gram onto disk, it might be
worth repeating that this tech-
nique can be used with almost
any machine-language pro-
gram. It will be necessary to put
the proper data into the BC, DE
and HL registers, and the JP to
the execution address will have
to be determined. Consequent-
ly, the user will have to perform
the same operations that we
have so far accomplished with
RSM2 for Pencil; that is, deter-
mine the start, end and execu-
tion addresses for the program
being processed. Then relocate
the program to unused memory
(6500 will usually be a good
choice for the TRS-80) and at-
tach a block-move routine. The
only differences involved in the
block-move routine will be the
byte count, destination address
and source address loaded into
the BC, DE and HL registers,
respectively, and the execution
address for the final jump.

Programming the Block Move
with RSM2

Programming the block move
with RSM2 is quite simple. The
command is E (for edit), fol-
lowed by the address to be edit-
ed and the appropriate machine-
language op code. Only the ini-
tial address where RSM pro-
gramming is to begin needs to
be typed in. After the appro-
priate machine-language op
bode for that memory location is
typed in, RSM2 will automati-
cally increment to the next ad-
dress, and only subsequent op
codes need be entered. Here is
what it will look like on the
TRS-80 display after typing the
command “E 7520”:

7520 00-F3, 00-21, 00-00, 00-65, 00-11, etc.

The first command (E 7520)
simply says edit memory start-
ing at address 7520 hex. RSM2
then will display this address,
followed by the current memory
contents, which should be 00
because we initially zeroed all
memory before starting this op-
eration (it is becoming increas-
ingly apparent that this initial
zeroing of memory was a pretty
smart move, right?). The user

now types in F3, which is the op
code for Dl, or Disable Interrupt.
RSM2 then digests this op code
and displays the contents (00) of
the next address at 7521 hex.

After F3 is entered, continue
by entering: 21 , 00, 65, 1 1 , 50, 43,
01, 20, 10, ED, B0, C3, 50 and 43,
in that order. Note that these op
codes are obtained from the op-
code column shown in Table 1.
After all the op codes have beer
entered, hit the Break key to fin-
ish programming.

For those of you who are
relatively new to machine-lan-
guage programming, it might be
worth mentioning that these
machine-language op codes
can be found in most references
oriented to Z-80 programming.
The Radio Shack Editor/Assem-
bler and William Barden Jr.’s
The Z-80 Microcomputer Hand-
book are two examples.

To double-check the program-
ming of our block move, get a
symbolic display with RSM2 by
typing “S 7520.” The symbolic
display should be identical to
that shown in Table 1, except for
the comments. If you made any
errors, go back and re-edit the
memory where the error was
made. When the block-move
mnemonics appear exactly as
shown in Table 1, we are ready
to put Pencil and its accom-
panying block-move routine on-
to disk.

Before putting our dormant
Pencil program on disk, it would
be a good idea to make a cas-
sette tape backup copy of the
program. In addition to the
security provided by a backup
copy, the cassette recording
procedure will demonstrate
another one of RSM2’s useful
utilities, which is to make sys-
tem tapes, either originals or
duplicates. In our case, we will
be creating an original.

To put our “modified” Pencil
on tape, give the following com-
mand to RSM2:

P 6500 7530 7520

This command says punch
(record) a system tape, record-
ing the data in memory starting
with a 6500 hex start address, a
7530 hex end address and a 7520
execution address. RSM2 will
then ask you to assign a file
name. Be sure to prepare the
cassette deck for recording

before entering the file name.

After Pencil is safely on tape,
you might want to try a little ex-
periment to make sure the dor-
mant Pencil program is capable
of moving and executing itself.
To activate the block move, give
the following command to
RSM2:

G 7520

This command says to go to
memory location 7520 and exe-
cute the program located there.
Upon entering this command,
Pencil will become operational
almost instantly, assuming you
made no mistakes. It is impres-
sive how quickly the block-move
routine relocates the 4028 (deci-
mal) byte Pencil program.

It is perhaps important to
mention that when Pencil is ac-
tivated with the “G 7520” com-
mand, it (Pencil) claims all
available memory by clearing it.
Consequently, the dormant Pen-
cil that was residing at memory
location 6500 hex will be wiped
out, and so will RSM2. But since
we have Pencil on tape, all that
is necessary is to reload it
before putting it on disk. This
can be accomplished either by
the usual system tape loading
procedure or, in our case, with
the Tapedisk utility.

To reemphasize, putting Pen-
cil on tape as we just did is op-
tional. We could have put Pencil
directly onto disk with Tapedisk
without this interim step. I have
found, however, that many indi-
viduals like to have a cassette
backup of disk programs . . .
just in case.

Putting the Program on Disk
with Tapedisk

If you did not activate Pencil
as described in the immediately
preceding step, it will not be
necessary to reload Pencil from
the tape we created. In either
case, the procedure for loading
the tape using Tapedisk is as
follows.

After bringing up DOS and
calling up Tapedisk, a question
mark prompt will be displayed.
Prepare the modified Pencil
tape in the cassette recorder,
type C and enter. Tapedisk will
load Pencil and retain control of
the computer.

After loading, another ques-
tion mark prompt will be dis-

played. At this point, you should
be sure to have a disk ready to
receive the new Pencil program.
The following command will
save Pencil to disk.

F PENCIL/CM D:0 6500 7530 7520

The F is the required Tapedisk
command for copying to disk (I
don’t know what F stands for—
maybe “From” memory to disk).
PENCIL/CMD:0 is the file name
to be written to drive 0, and the
user is, of course, free at this
point to make appropriate
changes, loading to a different
drive number or modifying the
file name. The rest of the com-
mand is the now familiar ad-
dress information in the usual
order: start, end and execution
addresses. These addresses
must be exact.

Upon entering the command,
Pencil will be transferred from
memory to disk. That’s it— we
are finished! Give it a try by call-
ing up Pencil with DOS. Pencil
should work almost instantly if
you did everything correctly.

Although the step-by-step
procedure as described herein
seems lengthy, it is really not all
that complicated. The length of
the instructions provided in this
article was intended to make
things as clear as possible for
the TRS-80 user who is relatively
new to machine-language pro-
gramming. After practicing this
operation a couple of times, it
should not take more than a few
minutes to put any system pro-
gram on disk.

To show that the procedure
can work with just about any
machine-language program,
part 2 will demonstrate essen-
tially the same procedure for
the “uncopyable,” although
slightly more complicated, Mi-
crochess 1.5. ■

Author’s note: When I initially
wrote this article, the Radio
Shack DOS 2.1 (disk operating
system software) was the only
DOS we TRS-80 users had avail-
able. In recent months, how-
ever, two disk operating sys-
tems have been released:
Radio Shack DOS 2.2 and NEW-
DOS by Apparat. (Editors’ note:
see next month’s issue for a re-
view of NEWDOS.) A third is on
the way: DOS 3.0, which is an
improved version of the original

52 Microcomputing, October 1979

WEB ^ ASSOCIATES

DOS 2.1 . The latter two systems
were both written by a gent
named Randy Cook.

The release of the first two
disk operating systems (NEW-
DOS and DOS 2.2) affect the
computer memory block-move
techniques discussed in my
two-part article; the potential
problem derives from the fact
that both of the new DOS sys-
tems insert a keyboard de-
bounce routine in the midst of
DOS RAM memory. The proce-
dures described in the article
main text will not function prop-
erly without some additional
software changes. These
changes— and they are brief-
are provided in the following
paragraphs.

As of the time of this writing,
I have not yet had access to
Cook’s DOS 3.0, so the ensuing
comments apply only to NEW-
DOS and DOS 2.2.

The Nature of the Problem

NEWDOS inserts its de-
bounce routine starting at
memory location 4378 hex, and
DOS 2.2 initiates its debounce
routine at memory location
43D8 hex. The problem occurs
when certain machine-lan-
guage files are loaded to high
RAM from disk and subse-
quently relocated from high
RAM to low RAM, thus over-
writing the resident DOS. (If
this is not clear to the reader,
read and understand the main
text of the article, then come
back to this errata).

When the resident DOS is
overwritten in this way, the
keyboard debounce routine, as
employed by both NEWDOS
and DOS 2.2, is also overwrit-
ten. Since the DOS keyboard
debounce routine makes up
part of the keyboard scan rou-
tine (the keyboard scan routine
continuously “looks” for
keyboard inputs), the effect is
that when the debounce rou-
tine is overwritten, the key-
board scan routine also gets
messed up and the whole sys-
tem crashes.

The NEWDOS Solution

For NEWDOS, the solution is
simple. The authors of NEW-
DOS thoughtfully provided a
means to defeat the keyboard

debounce routine: Simply hold
down, simultaneously, the
SHIFT and UP-ARROW keys
while either powering up or
reseting the the TRS-80. With
the keyboard debounce defeat-
ed in this way, the disk loading
and subsequent relocation of
machine-language files from
high to low RAM— as described
in the main text— will not cause
any crashes or problems. Your
keyboard debounce will be lost,
but at least you can still load
and run your low-RAM ma-
chine-language programs from
disk.

The DOS 2.2 Solution

The solution for DOS 2.2 is
not quite so simple; the DOS 2.2
authors did not provide a way
to easily defeat the keyboard
debounce routine. Consequent-
ly, more drastic methods are re-
quired to defeat the keyboard
debounce to overcome the
problem.

To defeat the DOS 2.2 key-
board debounce, it is neces-
sary to restore the keyboard
driver address in the device
control block (DCB) to its “orig-
inal” configuration (i.e., as it
was originally used by DOS 2.1).
This is not as scary as it
sounds. All that is required is to
change the driver address from
its DOS 2.2 configuration, 43D8
hex, to its “old” configuration,
03E3 hex. How do we accom-
plish this? Simple. Here is the
machine-language code for this
short routine:

OPCODE MNEMONIC

21 E3 03 LD HL.03E3H

22 16 40 LD (4016H),HL

This short and simple code
will defeat the DOS 2.2 keyboad
debounce if properly inserted in
your machine-language pro-
gram. Where should that be? I
recommend that you put it at
the start of the block-move
code that is developed in the
main text. Example 1, is a dupli-
cation of the Electric Pencil
block-move routine with the
keyboard debounce defeat rou-
tine inserted. Notice that the
memory address references
have been adjusted to accom-
modate the extra six bytes of in-
structions.

With this extra six-byte
patch, the DOS 2.2 keyboard

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v* Reader Service— see page 227

Microcomputing, October 1979 53

Memory Op Code

Mnemonic

Comments

7520

21 E3 03

LD HL.03E3H

REQUIRED DCB ADRS

7523

22 16 40

LD (4016H),HL

LD TO DCB

7526

DISABLE INTERRUPT

7527

21 00 65

LD HL.6500

SOURCE ADDRESS

752A

11 50 43

LD DE.4350

DESTINATION ADRS

752 D

01 20 10

LD BC,1020

BYTE COUNT

7530

ED BO

LDIR

BLOCK MOVE INST

7532

C3 50 43

JP 4350

JP TO EXECUTE ADRS

Example 1.

debounce will be defeated, but
your relocated low-RAM pro-
gram will load and run normal-
ly. Also note that your execu-
tion address will be at memory
location 7520.

It is, perhaps, useful to note
that the Electric Pencil does

not require this debounce de-
feat because the Pencil em-
ploys its own keyboard scan
routine. The Pencil was used
here only as an example. In part
2 of this block-move article,
which addresses the applica-
tion of the block-move tech-

niques to Microchess 1.5, it will
be necessary for the reader to
insert the six-byte debounce
defeat, as described herein, in a
similar manner. This operation
will be left as an exercise for
the reader.

Other low-RAM machine lan-
guage programs, such as
T-BUG, Microchess, AIRAID
and so on, will require the de-
bounce defeat instructions if
you are using DOS 2.2. But if
you are using NEWDOS, the
solution is much simpler. Mere-
ly defeat the NEWDOS key-
board debounce as described
above; it is not necessary to in-
corporate the six-byte code as
is required for DOS 2.2.

By the way, for you NEWDOS

users who wondered about the
“Appendage” and the “Disable
Interrupts?” prompts used by
the LMOFFSET module, the an-
swer as to what these are
should be obvious after you read
my article. The Appendage is
the block move routine (LD BC,
LD DE, LD HL and LDIR), and the
Disable Interrupts? query simp-
ly refers to the Dl (OP CODE F3)
instruction. You should always
Disable Interrupts when doing
a block move of any kind with
the TRS-80.

That’s about it, folks. By the
time this is published by Micro-
computing , Cook’s DOS 3.0
should be on the streets. With
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your own.

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54 Microcomputing, October 1979

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v* Reader Service— see page 227

Microcomputing, October 1979 55

Anatomy of a Scam

Remember World Power Systems? Here’s the story on how that world crumbled.

Terry Kepner
Instant Software Staff

C olonel Winthrop” is a
name that strikes terror in-
to the heart of any microcom-
puter businessman or hobbyist
who depends on mail-order
business.

Colonel Winthrop; alias David
Winthrop; alias Harry Hunt;
alias Jim Anderson (alias ?) has
done it again. This time it was
called World Power Systems,
Inc. World Power Systems
(WPS) was not incorporated,
neither did it have a business
license.

What it did have was an of-
fice at 1 161 N. El Dorado Circle,
Tucson, Arizona; three self-
storage lockers of computer
components and related equip-
ment; office supplies; many
bewildered employees; four (or
more) bank accounts; a few
hundred thousand dollars of
debt; and hundreds of upset
and dissatisfied customers and
suppliers. All this in only four
months!

How did it happen? How did
it start and how did it stop?
How does someone get the
money and hundreds of thou-
sands of dollars of credit in
only a few months— especially
someone who is wanted on a
federal warrant as an escaped
convict?

Of course, Colonel Winthrop
does have a few advantages:

He’s an electronics technician
who knows more than enough
to design and build a micro-
computer, and he is a very per-
suasive talker who can throw
enough bull to get out of almost
any jam.

Actually, if he was willing, he
could probably set up a legiti-
mate computer business and
make a good profit for himself.

The Beginning

It began in January 1979,
when Perry Pollock, an Arizona
resident, signed contracts with
Jim and Lee Anderson estab-
lishing a company to be named
World Power Systems, Incor-
porated. These contracts es-
tablished Perry as R & D man-
ager, Lee as vice-president and
Jim as president of the corpora-
tion. Mr. Pollock would help
supply the venture capital and
credit, while Jim and Lee sup-
plied the technical expertise.

Phase I

With these contracts, they
applied for a business loan us-
ing Perry’s established credit
history as a major reference.
The money they received went
toward office rent, storage
locker rent, some R & D work
and advertising layouts.

They then applied to Leasa-
metrics of San Diego, California,
for leasing credit to acquire of-
fice equipment and furnishings.
Leasametrics performed a cred-
it check on the reference sup-
plied, Mr. George Pollock, and
contacted the bank that had

lent them the money. Satis-
fied with this check, Leasamet-
rics OK’d the credit and sent
the items WPS had requested.

For a while things were quiet
as WPS laid the groundwork for
the next step. An advertising
campaign was planned and ad
sheets prepared. Several maga-
zines were approached about
advertising rates and printing
deadlines. When the ad sheets
were ready, they were sent to
the magazines, along with the
payments for advertisements.
Locally, in Tucson, WPS began
making purchases of equip-
ment from the Byte Shop and
Radio Shack, also by paying in
full. They also made a few out-
of-state purchases, always in-
cluding the payment with the
order.

When the magazines came
out, orders started to come in
to WPS. At first the orders were
filled and shipped promptly,
but as the orders increased
WPS began to fall behind in
their shipping. Customers were
sent stalling letters. These let-
ters blamed WPS suppliers with
failure to supply needed mer-
chandise as rapidly as had been
promised and cited this as the
reason for the delays in ship-
ping the customers’ orders.
WPS did promise to ship the
merchandise as quickly as pos-
sible and asked the customers
to please be patient.

Phase II

Then the funny stuff started.
Using Leasametrics as its ma-

jor reference, plus its reputa-
tion at the local Byte Shop and
Radio Shack, WPS began to
ask their equipment suppliers
for credit on their orders.
Because of WPS’s previous
practice of prompt payment
and their good credit check, the
vendors usually agreed to this
simple credit request.

Things moved into high gear.
WPS placed orders for large
quantities of equipment: disk
drives, RAM chips, circuit
boards and practically anything
else dealing with computers.
These orders were usually
placed by the use of a purchase
order, with instructions on
where and how to receive pay-
ment for the items on the order.
These instructions included the
statement that payment would
be made in about 30 days.

As their reputation, a good
one so far, spread, more people
ordered merchandise from
WPS. By the time their second
advertisement was released
they were doing a booming busi-
ness, and they hired more help,
including two office secretaries
to handle all the incoming
phone and mail orders.

With the announcement of
the availability of a Radio
Shack-compatible disk drive
and a replacement unit for the
RS interface, the number of
orders increased to a veritable
flood. There were dozens of
phone orders and scores of
mail orders streaming in daily.

Almost all the orders In-
cluded payment, and, as a re-

56 Microcomputing, October 1979

suit, the WPS bank accounts
grew rapidly. However, the
shipping department was hope-
lessly behind by then. For every
ten orders that came in, only
one was filled and shipped; the
backlog of orders would take
months of hard work to fill and
ship. And that would be if WPS
ceased taking any more orders
and concentrated only on the
shipping department. The em-
ployees knew this and won-
dered why the production
facilities were so slow. They
were given the line about the
vendors being late in their ship-
ping, which slowed down WPS
production. Because of this
and because WPS was still
shipping things out, the
employees were not suspicious
about the real intentions of the
head people.

Phase III

WPS initial credit orders
from their vendors began to be
due. This was usually indicated
by a letter from the vendor in-
quiring as to why he had not
been paid, and politely request-
ing payment. These suppliers
were sent stalling letters, usu-
ally saying that the statement
from the vendor had been mis-
laid and the letter had arrived
too late for the current billing
cycle, but that the payment
would be sent within the next
two weeks.

Some vendors called instead
of writing; they were told the
same story. These tactics usu-
ally sufficed in delaying the
next letter or call for at least
three weeks, sometimes for as
long as two months.

At this point, before WPS
credit was canceled because of
nonpayment, more merchan-
dise was ordered from the sup-
pliers. These new shipments
further lulled the suspicions of
the employees by making it
possible for them to fill and
ship some more orders, which
in turn satisfied some of the
customers and gave credence
to the claim that WPS was at-
tempting to fulfill its obliga-
tions. In Tucson, they were fill-
ing orders quickly to prevent
any immediate problems with
the local authorities. For the
same reason, they were also

keeping the rent payments and
employee wages on a business-
like and timely basis.

Under normal circumstances,
this phase of the scam would
last for about two months. Or-
ders would come in by the hun-
dreds, and only enough would
be filled and shipped to prevent
the complaining customers
from going to the proper author-
ities. Naturally, those that com-
plained the loudest would have
their orders filled first. Also, the
creditors would be put off even
more, usually by claiming that
the vendor’s statement was in
the billing process and would
soon be mailed. When this did
not work, the trick was to say
that the payment was in the mail
and to request notification if it
wasn’t received within the fol-
lowing two weeks.

And the orders would still
come in.

Phase IV

Eventually, everything would
come to a head. The creditors
would threaten to go to the po-
lice and courts for their money;
the customers would threaten
to go to the Better Business
Bureau and to the police to get
their equipment. At this point
Phase IV would be initiated.
This would entail cleaning out
the bank accounts, shifting the
merchandise around from one
location to another and leaving
a confusing trail as to its exact
location— and setting up a fall
guy.

The fall guy would be a prom-
ising and unsuspecting em-
ployee whom they had been
carefully leading on. He or she
would be told that because of
his/her extremely good busi-
ness sense and/or aptitude that
the company was going to pro-
mote him/her to president of the
company.

This person is usually the
sales manager or an assistant
to the current president or vice-
president. The “president-elect”
is given a short training period
and then given a raise. After on-
ly a few days, he/she is told the
other officers are taking a much-
needed vacation for a week or
so and that they will see him/
her later. Before they give the
new president the keys, they

clean out the business of all
valuables they can take. With
these items they leave the
state. In fact, they take with
them the money from the
customers, the merchandise
from the vendors and the
reputation of the company.

A week or so later, the new
president goes to work and
finds the police there waiting.
He’s arrested, and the police
waste time investigating him
and the rest of the employees
while the principals of the scam
use the extra delay time to hide.

Using only a fraction of the
stolen money, they set up shop
in another state and resell the
defrauded merchandise to new
customers at a big discount,
unloading the equipment rapid-
ly enough to prevent word from
reaching the police in the state
from which they fled. After they
have sold off the equipment
they leave for a third state and
begin new lives, much richer
than they were before.

Typically, such a scam will
net the principals an average of
$100,000, although it could yield
as much as $500,000 clear prof-
it, with no income tax.

The Collapse

Fortunately, this scam ended
differently. Some bounced
checks to suppliers, persistent
questions from Bill Godbout
and some prying by John Craig,
former editor of Kilobaud ,
forced Anderson’s hand. Know-
ing that he might be identified
by Craig, Anderson decided it
was time to leave town.

He decided that the first load
would leave the next night,
April 25. For some reason, he
decided to take along two of
the employees, Eva and Joan.
Both were 21, both working at
WPS since early March, and
both were unsuspecting. He
told the two women that they
were going to go to a computer
school in Florida at company
expense. He also told them that
everything connected with this
move was top-secret informa-
tion. They were not to tell their
parents where they were going,
how long they would be gone or
even why they were going. They
were told that while they were
gone they would not be allowed

to contact their parents for any
reason. In order to get them to
do this, Jim cited industrial es-
pionage as the reason for the
secrecy.

In fact, it was so secret that
they were told not to disclose
the location of Jim Anderson’s
residence, which was also be-
ing used as a base for operat-
ing the scam.

Eva went home from work
and started to pack. She re-
fused to tell her parents any-
thing except that she was go-
ing to a computer school and
couldn’t tell them anything
more. As soon as she finished
packing she left for Jim’s house,
where she was met by Jim and
Joan. Shortly after she arrived,
they left in a van full of comput-
er equipment.

Eva’s father was very upset
by this sudden departure, and
he was also suspicious of Jim
Anderson’s motives. He decided
to call a relative of his, Bob Gil-
martin, a highway patrolman
for the department of public
safety.

Together they went to Joan’s
house and talked to her parents.
Her parents knew as little as
they did about what the two
women were involved in with
WPS. However, they did re-
member hearing Joan mention
that Jim’s house was within
sight of Magee Junior High
School.

Armed with this bit of infor-
mation, Eva’s father and Patrol-
man Gilmartin drove up and
down the side streets surround-
ing that school.

At 4 am, April 25, they found
Eva’s and Joan’s cars. They
took Eva’s car home and called
Joan’s parents to tell them
where her car was so they could
go pick it up.

At 8 am they set up surveil-
lance in front of Jim Anderson’s
residence. Shortly thereafter,
Lee Anderson left the house,
and they trailed her. Unfortu-
nately, they lost sight of her at
Speedway and Kolb, about three
miles from where they started.
They decided to stop at a near-
by store so that Bob could call
in to work.

Because of the circum-
stances, when the Pima County
attorney’s chief criminal deputy

Microcomputing, October 1979 57

heard the story, he decided to
assign Investigative Agent Su-
san Moore to the case. Susan
rapidly verified that everything
at WPS was not on the up and
up. She spent most of her time
Friday following Lee Anderson
around town.

Late Friday afternoon (or eve-
ning), Eva called her father from
the Holiday Inn in Carlton, Tex-
as. While she, Joan and Jim
were driving from Tucson to
Texas, Anderson had led them
to believe that the things in the
van were not really going to
Florida at all. In fact, the things
in the van were not paid for yet.
Certain statements by Ander-
son further led them to believe
they were going to stop in Tex-
as and set up a new business
and sell the merchandise in the
van.

As they continued to travel
across Texas, Eva and Joan
learned that the things in the
van had already been sold to
other customers, and that Jim
was not going to send the mer-
chandise to them. Eva and Joan
had thought that the equip-
ment was legal and that they
were taking it to a major buyer.
They were wrong.

In short, the two women dis-
covered that Jim Anderson in-
tended to defraud his previous
customers and his vendors, with
the two of them as his accom-
plices.

Eva decided that she wanted
no part of this and managed to
sneak away to call her father
for help. He told her to remain
where she was while he sent
the local police to place her in
protective custody until he
could fly out there to get her.
She was back in Tucson Satur-
day morning.

That afternoon, Eva talked
with Susan Moore and told her
everything she knew. She told
Susan about three self-storage
lockers buildings where she be-
lieved WPS had kept merchan-
dise, but she didn’t know the
exact unit numbers. Two were
on Speedway and the other was
on Tanque Verde.

The police watched all three
buildings, along with the Ander-
son house, the rest of Saturday
and on Sunday, but nothing
happened.

On Monday the pace picked
up. At 7:05 am, one of
Anderson’s neighbors, whom
Susan had talked to in the
course of her investigation,
called Susan at home and told
her that people were moving
things out of the house and into
a van. After thanking her,
Susan called her office to in-

form them of the activity and re-
quested assistance. Robert
Treadway, another investigator
with the Pima County attor-
ney’s office, overheard Susan’s
request for assistance on his
radio while starting for work
that morning. He went to assist
Susan, who, by this time, was
following the van to an unknown
destination.

The message was relayed to
Paul Banales, one of the coun-
ty’s prosecuting attorneys. He
left immediately with another
house investigator, Ken Janes.

At this point, the action had
moved and was no longer at An-
derson’s house, but at another
located on East Julia, approxi-
mately three miles from Ander-
son’s. Perry Pollock and his
brother-in-law were observed
unloading the contents of the
van into the house.

When Paul finally arrived,
there were two unmarked coun-
ty attorney vehicles parked
across the street from the
house, with the passengers in-
tently watching the activity.
But no one noticed!

Susan left to maintain sur-
veillance on the Anderson resi-
dence. However, as a result of
her police radio going dead,
she was forced to return to the
office to obtain another vehicle.
She was accompanied, at this
time, by Paul, who fortunately
had a walkie-talkie unit with
him.

Meanwhile, Perry’s brother-
in-law and an unidentified
woman left, followed by one of
the cars. She went to three
banks— one right after the
other— the First National Bank,
the Valley Bank and the Great
Western Bank. The account at
the Great Western Bank was
Mr. Pollock’s personal account,
the police later discovered.

Things were happening a lit-
tle too fast for Mr. Banales’
comfort, so he decided to ar-
rest Perry Pollock and obtain a
search warrant for the East
Julia residence before any
items were moved any further.

The warrants were served at
2 pm Monday, at the East Julia
residence, and Perry was taken
into custody. He was released
later on his own recognizance,
pending filing of formal
charges.

In the house, the police found
computer equipment in the liv-
ing room and bedrooms; some
paperwork and documents,
small office supplies and equip-
ment; and most important, they
found a set of house keys. These

were identified by Eva, who had
accompanied the police, as be-
longing to the Anderson house.

Because of the evidence
found at Perry’s house, the
police were able to obtain a
search warrant for Jim Ander-
son’s house, which was issued
at approximately midnight.

Using the set of keys, they
entered Anderson’s residence
at 1 am Tuesday. They found
reams of paperwork, docu-
ments, office supplies and
equipment, and computer
equipment. Numerous trash
bags full of shredded docu-
ments were found. The police
spent the entire night seizing
everything related to WPS. In
the midst of all these items,
they found a contract leasing a
particular storage locker, giv-
ing both the location and unit
number. This contract had
been signed by Joan at the re-
quest of WPS. Eva was ques-
tioned about this, and she
related that Joan had, in fact,
rented a storage locker for WPS
at 4115 East Speedway; the
lease confirmed this. Further-
more, Susan’s check with the
manager at the other storage
locker on East Speedway re-
vealed that Lee Anderson had
rented a locker at Kolb and
Speedway for WPS. Since the
police could positively locate
two of the three lockers, they
proceeded to pick up two more
search warrants, again citing
“probable cause” as justifica-
tion. These were issued at 10:30
am Tuesday, May 1.

The first locker, in Lee Ander-
son’s name, was on the far east
end of Speedway Blvd. It ap-
peared to contain many of Perry
Pollock’s personal belongings,
but there was also equipment
for circuit board fabrication
and layout; artwork and pho-
tography; and photosensitive
boards and developing chemi-
cals.

The second storage locker, a
15x12 foot unit, proved to be
the jackpot. It was crammed
with computer equipment,
which ranged from small RAM
chips to complete computer
systems. There were hundreds
of disk drives, photosensitive
circuit boards, chemicals and
other items. The police tallied

Colonel Winthrop, alias Jim Anderson (?).

58 Microcomputing, October 1979

PET 2001 • PET 2001 • PET 2001 • PET 2001 • PEI 2001 • PET 2001 • PET 2001

roughly a thousand boxes re-
moved from this storage locker,
many still sealed with original
packing slips included. There
was so much stuff that they
had to call for the department’s
moving van, normally used only
to haul tons of illegal drugs to
disposal areas.

Preliminary estimates indi-
cated that well over half a mil-
lion dollars’ worth of equip-
ment was recovered, perhaps
as much as $750,000.

The third locker unit was on
Tanque Verde, but because the
police did not know the exact
unit number and because they
could not identify any of the
names on the storage building’s
registry, they were unable to

get a search warrant. The police
are still watching the building
for any familiar faces or unusu-
al activities. In addition, the
owners of the storage lockers
are also checking those units
that have defaulted on their
payments to see if any of them
contain anything that might be-
long to WPS.

Jim Anderson and Lee Ander-
son managed to escape with an
estimated $100,000 worth of
equipment, and an unknown
amount of money. The police
know that Jim did unload his
van into a storage locker in Tex-
as; however, Anderson was one
step ahead of the police. By the
time federal authorities were
called in to assist in obtaining a

warrant for the Texas locker,
Anderson had already cleared
it out, leaving only a few boxes
of equipment.

The Jig Is Up

There is a good ending to
this. As of June 2, Jim and Lee
Anderson were arrested in
Honolulu, Hawaii, with approxi-
mately $11,000 cash. Jim was
actually in the process of dying
his hair when the FBI broke into
his apartment to arrest him.

As a final wrap-up, Jim is be-
ing arraigned in California on
his outstanding federal warrant
for escape, while Lee is being
returned to Tucson to be ar-
raigned on charges stemming
from the operation of WPS.B

Anyone having any additional
information on WPS is request-
ed to contact either:

John Zemblidge
Postal Inspector
Box 26070
Tucson AZ 85726
or

Paul Banales
Deputy County Attorney
Pima County Attorney’s Office
111 West Congress St.
Tucson AZ 85701
(602) 792-8411.

The names of WPS employees
have been changed in the inter-
est of personal privacy.

The Pima County attorney’s of-
fice has reviewed this article
and OK’d it for publication.

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Microcomputing, October 1979 59

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Business Software Made Easy

If you want to write business software, you should read this article.

S o, you’d like to write some
business software? It isn’t
too difficult, so why play games
when your micro could be mak-
ing a few bucks. The problem in
writing good business software
is that programmers are neither
accountants nor businessmen,
and vice versa. Without trying to
be expert in all these areas, this
article will point the would-be
software person in the right
direction and perhaps give away
a few tricks of the trade in the
process.

As you approach this subject,
keep in mind that there are
several different ways to solve
almost any problem. Although
the CPAs, IBM and all the other
big professionals do a great job
for big business, it is OK if we
think a little smaller for the
small business— but not quite
as small as some advertising
would have us believe. No mat-
ter how small the business, the
software system must be fast,
accurate, operator proof and
produce good, readable hard-
copy output. But we can cut a
few corners and frills.

Defining Software Needs

The businessman who begins
to think about computers most
often mentions payroll and in-
ventory, two aspects that might
better be left until he and the

computer are better acquainted.
Also useful to him are check reg-
isters and mailing lists (easy),
general-ledger accounting
(tougher), accounts receivable
and a lot of specialized items
such as payment schedules and
investment returns.

All this can be done, of
course, with pencil and paper;
the computer is simply faster
and more accurate and be-
comes cost effective only above
a certain volume. Cost effec-
tiveness is the businessman’s
bible, and sometimes comput-
erizing just isn’t worth the trou-
ble and expense. If he can’t af-
ford more than a stripped-down
game-playing machine, he can’t
afford any decent software
either.

There is a lot of software on
the market, some good and
some bad, costing from $15 per
program to $15,000 for complete
packages. The point is that no
one program or package will
satisfy the needs of even the
smallest business or of all
businesses in the same cate-
gory. Most will need individual
customizing, at the very least.
Some professionals, too, such
as doctors, will be mainly in-
terested in accounts receivable,
while a parts house might get by
with only a decent inventory pro-
gram. All of these needs require

legitimate business software,
and the guy doing this for
dollars can pick and choose,
leave out the trivia, beef up the
important stuff or even write it
all if he has the time and the
skill.

In any event, the useful soft-
ware package will consist of
several programs and data files,
compatible with one another
and linked together in some
manner such as sharing a com-
mon data base. Fig. 1 outlines
an actual small-business gen-
eral-ledger system. Considering
all of the paperwork of a typical
enterprise, the general ledger is
neither the most difficult nor the
easiest to do, but is always
essential. Its purpose is to ac-
count for the money.

In accounting jargon, a jour-
nal is a diary-like listing of all
transactions. At the end of a
specified accounting period, the
entries are posted, that is,
copied into ledgers, where they
are grouped by type rather than
in chronological order. Each
transaction gets entered at
least twice, hence the term
double-entry accounting. Forex-
ample, a cash sale increases the
cash and decreases the goods
on hand.

At the level we are speaking
of, accounting consists of first
making the original entries, then

separating them by specific ac-
count type and, finally, manipu-
lating the result into some
meaningful form such as a prof-
it/loss report. Fig. 2 shows the
flow of entries just described. At
this point it should be apparent
that, whether done by hand or by
computer, some kind of sorting
is essential.

In Sorting and Searching ,
Donald Knuth estimates that 25
percent of business-computer
time is devoted to sorting. Some
guesses place the figure even-
higher. Volumes have been writ-
ten on the subject; we can skip
the exotic math used in sorting
IRS records, for example, but we
should be prepared to do some
sorting.

Reordering a list of a few hun-
dred simple numbers should not
pose any great problem. Most
BASICS have a means of ex-
tracting the first character of a
string, which may then be con-
verted to a number for rough
alpha sorting. To do a more
thorough job, there are available
little code books that assign a
unique number to each name.

So much for ascending or
descending order; it is also
useful to sort or, more precisely,
to group items having some
common characteristic, such as
an account number. It is a busi-
ness convention to use a chart
of accounts, which in a simple
example might code all cash
transactions, all charges, all in-
ventory, and so forth.

Sorting

To the accountant, each
transaction is a journal entry. To
the programmer, each such en-
try is a record. A collection of
these can be called a journal or
a transaction file. Each record
contains several different
pieces of information, which
we’ll agree to call fields, and

PROGRAM

"TRANSACT’

PROGRAM

LEDGER

"LEDGERS"

TRIAL BAL

PROFIT/LOSS

PROGRAM

BALANCE

'BALANCE'

SHEET

Fig. 1. A simple general-ledger system.

60 Microcomputing, October 1979

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Microcomputing, October 1979 61

several records of like type
make up a file. Fig. 3 outlines a
typical general-ledger record as
it would appear in the transac-
tion file. Notice that the date is
one field, the account number
another and so on. Why is it
done this way?

The programs are going to be
reading this file— probably
many times— as a series of nu-
meric and string variables. This
particular record would be read
as A,D$,B,A$,D,C. The fields are
kept separate so that we can ex-
tract the date field, D$, and use
it in sorting by date.

In this case, A is the account
number and will be used to route
the journal records into the
proper ledger account. This is
done by reading the first number
from a list of the chart of ac-
counts— either out of another
file or out of an array— then, in
turn, comparing each record
with that number. This is re-
peated with each account num-
ber. During the process, the
records that are identified may
either be printed out in order or
written into a sorted file, or both.
This is not a fast method of sort-
ing, but I doubt that your printer
can stay ahead of it. (See Fig. 4.)

In addition to sorting, we have
been speaking of printing and of
repeatedly reading files. This, in
effect, establishes a minimum
hardware configuration for run-
ning business software. Oper-
ators can’t afford the hassle of
wading through audio cassettes
looking for a particular record,
and the businessman who
doesn’t want his records on
paper should have disappeared
by now. A good printer is essen-
tial, along with either a disk or a
sophisticated tape system; a
single mini-floppy will do
wonders, but even 64K of RAM
and the world’s fastest CPU of-
fer no particular advantage.
There is little actual computa-
tion involved, but a heck of a lot
of searching and printing.

In fact, these disk files are the
complete and final answer to
modern business processing. In
addition to their main purpose,
the storing of records, they may
be used in a lot of ways to make
everything run smoother. Forex-
ample, the numbering of files
usually begins with 1, but the

JOURNAL

LEDGERS

REPORTS

Fig. 2. Transaction flow.

file addressing starts at zero. If
records are 100 bytes long, there
is a 100-byte space at the start
of each file for maintaining con-
venient access to often used
housekeeping data, such as
dates, headings and informa-
tion about the file itself.

One typical use is to enter the
date each day when the ma-
chine is turned on and use this
to properly head up each docu-
ment printed that day. Fig. 5
shows a way of using the file
space just described.

Operation

Having briefly covered some
general concepts and a few de-
tails, let’s go over the actual
operation of the general-ledger
system in Fig. 1. I hope that at
this point it makes more sense
than it did at first glance.

The operator begins by load-
ing the program, Transact. This
program serves several func-
tions. One part merely services
the chart of accounts and will
seldom be used after the refer-
ence file, Chartac, has been
established. The essential activ-
ity in this program is entering
transactions as they occur, in
chronological order, in the file
Journal. At the end of some peri-
od, such as after each month,
this file will presumably contain
all the raw data necessary to
complete the rest of the general-
ledger accounting. It is almost
the only manual part of the
operation.

One of the operator options in
Transact is to call for posting.
When this is done, the program
calls Ledgers and sets the post-
ing process in motion. This pro-

5 BYTES

12 BYTES

5 BYTES

A$ - 20 BYTES

5 BYTES

Fig. 3. A typical file record.

III

DATA

III

112

113

140

150

200

J 112

AFTER

Fig. 4. Records before and after sorting.

FILE INFO

DATE INFO

HEADING INFO

ADDRESS 0 ADDRESS \ ->

FIRST "REAL" RECORD

Fig. 5. Temporary file at 0.

gram reads the file Journal,
sorts or groups the records ac-
cording to their account num-
ber, prints them out and writes
the totals of each ledger
category into the file Sorted.
Upon completing this, it takes a
trial balance (an essential ac-
counting function). If the
balance is zero, Ledgers will pro-
ceed to crank out a profit/loss
statement for the period, using
information stored in the file
Sorted.

The final program of the set is
Balance; this also works from
the file Sorted to produce a
balance sheet. It also identifies
and carries forward, in the file
Balfwd, the accounts that have
to be preserved for the next ac-
counting cycle.

In summary, there are three
programs and four files. The op-
erator manually enters raw data
in the first file; with very little
human intervention, the pro-
grams then derive from this in-
formation all the remaining files
and reports. The machine does
the work, and this is as it should
be in the modern world.

Documentation

Remember that the operator
may not have the slightest in-
terest in how the program works
and may consider its use just
another chore. You’ll be sur-
prised, too, how soon you can
forget the details of a program
you are not using constantly,
and how obscure it might seem
to someone else called in to
debug the system. In addition to
plentiful remarks in the program
itself, a detailed instruction
manual is a must for any busi-
ness software system.

When you think it is perfect,
try it on an inexperienced
operator and then rewrite it. Try
entering bad data and then build
in traps to preclude such
disasters. Imagine all the things
that can go wrong during “nor-
mal” operations (such as power
failures) and carefully explain
how to recover.

Business software can be as
challenging and as much fun as
any other kind of programming.
It’s a good answer to “What do
you do with your computer?”
and you just might get rich do-
ing it.H

62 Microcomputing, October 1979

Radio Shack introduces
its second TRS-80* computer breakthrough.

A small-business computer for people who like to
pay less than the “going price”.

Why Radio Shack's " going price" is
so much lower

There’s TRS-80 Model I. Systems start at
$499. Last year they started at $599, but
now we're down the learning curve while
others are just starting up. This ad, of
course, is not about Model I. It’s about
Model II. Model II systems start at $3450.
It’s an all 8" floppy disk system: one built
in, room for three more. True 12" monitor,
twice the size of the IBM 51 10, for exam-
ple. Twice the operating speed of Model I.
Upper and lower case. New state-of-the-
art 76-key keyboard. Level III expanded
BASIC. And here’s what’s so incredible:
comparable systems (like IBM 51 10) cost
roughly 33% to 66% more. We said we’d
tell you why; it’s a mix of three pos-
sibilities: (1) they have higher selling
costs, (2) they have higher manufacturing
costs, (3) we have lower gross margins.

A small business may be a small
part of a large business, right?

Most businesses, small or large, have a
tendency to buy too much computer for
their job. We learned about this with

TRS-80 Model I; in fact Model I is too little
computer for many business applica-
tions. So we designed Model II to be “just
enough computer" for most micro/mini
applications. And here’s a promise: we’ll
sell you what you need, not less, not
more, and you will SAVE MONEY

Does a retailer belong in the
business-computer business?

The competition would like you to believe
computers can’t be sold over the counter
like typewriters. They’re right! Business
computers like TRS-80 Model II have to
be sold where computers and software
are sold, where computers are serviced,
where computer advice is available
directly from the manufacturer. That,
friend, is exactly what Radio Shack
is all about.

How we sold over 100,000
TRS-80 Model I Systems

This is probably the most interesting
computer story never told. We did not
know — repeat NOT know — there was a

big market for personal computers. So we
put 20 people on the job. Shortly there-
after we had over 700 people on the job.
The over 100,000 system sales came from
getting off our behinds FAST and meeting
demand by building computers (instead
of talking about them).

Radio Shack deserves to be your
small-computer company!

Simply because we offer 5-figure com-
puting power at a 4-figure price — with
five business software packages ready to
“go to work” immediately — with your
existing personnel. Plus, modular design
means easy expandability with plug-in
printers, additional disk drives and more!
You can order a TRS-80 Model II (or I) in
over 7300 locations worldwide. And, over
100 USA Computer Sales/Service centers
are ready to stand behind your computer
with service (and training classes, if you
wish). There’s so much to tell about
TRS-80 II, we urge you to come in today
and get all the facts, firsthand!

* Retail prices may vary at individual stores and dealers.

Title

Company.

Street-

City _

V 2 -Megabyte Basic

System $ 3450*

Mail to: Radio Shack, Dept. CE-202

1300 One Tandy Center, Fort Worth, TX 76102

f f Vf A0 M

yea □ Send me your new 1980 TRS-80 Computer Catalog
□ I’d like more facts — have a representative call me

Name.

KIMCTR Measures Capacitance

This enhancement to KIMCTR (May 1979) results in a Ipf to 999.999 uF capacitance meter.

Clement S. Pepper
3270-96 Caminito East Bluff
La Jolla CA 92037

I f you are using KIMCTR (Kilo-
baud MICROCOMPUTING ,
May 1979, p. 34), you will be in-
terested in this low-cost
scheme for measuring capaci-
tance. If you are not using KIM-
CTR, this may give you the urge
to do so. If you have no inten-
tion of using KIMCTR but do
want to measure capacitance,
read on because this circuit
can be employed with other mi-
croprocessors, counter/timers
or just an oscilloscope alone.

I have many capacitors on
hand— most of them used—
that I have acquired from vari-
ous sources. Many capacitors
have unreadable markings;
some have in-house markings
that tell me nothing. So for
some time I have thirsted for a
simple, low-cost way to mea-
sure capacitance. There are al-
so times when I need to know
the value of a capacitor to
some reasonable accuracy.
More often I simply want to
match capacitance. This circuit
meets all of these needs.

The Concept

If you charge a capacitor at a
constant rate, its voltage will

increase linearly with time. If
you properly scale the charging
current and measure the time
required for a precise, one-volt
increase, the value of the ca-
pacitance will be proportional
to the transition time.

In this scheme I employ four
switch-selected constant cur-
rents of 1, 10, 100 and 1000 pA.
A low-high limit comparator de-
tects a one-volt change in V c
and provides a pulse out. The
pulse width is measured and
displayed on KIMCTR. It may
also be observed on an oscillo-
scope or measured on any suit-
able timer. Measurement span
is 1 pF to 999.999 uF on KIM-
CTR, with four ranges.

Parts cost is low— anywhere
from about $10 to $50, depend-
ing on what you have on hand
and where you buy needed
items. You can use an unused
flip-flop and exclusive OR gate
in the KIMCTR circuit to save
two ICs.

Though the concept is sim-
ple, some effort is required to
ensure accuracy of the mea-
surements. Access to a 4 V 2 dig-
it DVM with 10 nAand lO^V res-
olution is needed for calibra-
tion. There are few constraints
on construction; I built mine up
on perfboard. The primary con-
cern is to keep wiring short in
the capacitor circuit to mini-
mize stray capacitance. You
should exercise the usual care

with the comparator wiring to
minimize coupling between in-
put and output. I used five-way
banana jacks for connection to
Cx.

Basic Principles

An ideal capacitor that is
charged from a constant cur-
rent source will develop a volt-
age that increases linearly with
time. Assuming a zero initial
voltage and commencement of
current flow at start time, t 0 , the
voltage at any later time, t n , is
shown in Example 1.

Fig. la shows a constant cur-
rent source charging a capaci-
tor. The current must be truly
constant over some defined
range of v c for v c to be a linear
function of t n .

In Fig. 1b, C is bypassed with
a shorting switch. A voltage
comparator is connected across
C. The non-inverting input is
connected to C. The inverting
input is connected to a stable
voltage reference. At start time
t 0 , the switch is opened and a
voltage is developed across C.
At some later time, t 1f v c = v R ,
and the comparator output
changes state. If V R = 1 .000 volt
the differential time will be pro-
portional to C. However, this is
not a practical circuit because
the switch will have some resis-
tance and the initial value of C
will not be zero.

The effects of switch offset
are eliminated in the low-high
limit detector of Fig. 1c. Resis-
tor R1 is selected such that the
low-limit voltage, v c1 , will be
greater than any expected off-
set. Current source 12 main-
tains a precise 1.000 volt drop
across R2. Then v c2 - v c1 = 1.000
and C = |(t 2 — t!).

The outputs of the two com-
parators in response to the ris-
ing capacitor voltage are dia-
gramed in Fig. Id. Charging

begins at time t 0 . The low-limit
detector changes state at t 1f
the high limit at t 2 .

We need a scheme to mea-
sure the difference time. The
exclusive OR gate provides a
solution. Its truth table is pro-
vided in Fig. 1e. The gate output
will be high in the interval ti -t 2 ;
at all other times, it will be low.
The pulse width is the value of
C.

The Transistor Current Source

A single-transistor current
source provides the capacitor
charging. The basic current
source circuit is shown in Fig.
2. This simple circuit will
source a consistent constant
current with a high degree of
stability. The transistor is oper-
ating in a dc common-base con-
figuration. The voltage refer-
ence, VR, establishes a con-
stant voltage between the base
and emitter. The emitter cur-
rent IE must adjust itself so
that the product IE- RE = VR.

There are two inherent fea-
tures of the common-base mode
that contribute to its utility as a
constant current source: The
leakage current, Ico, of the col-
lector-base diode is not ampli-
fied by the transistor, and the
output resistance of the tran-
sistor is the dynamic source re-
sistance of the collector. For
small currents this will be many
megohms.

Care must be exercised in
the design and adjustment of
the current source, as the ac-
curacy of the measurement is
dependent on both the abso-
lute value of the charging cur-
rent and upon its remaining
constant throughout the mea-
surement interval.

The Measurement Circuit

The complete circuit is shown
in Fig. 3. I have identified the

where I = the charging current from the constant current source, and C =
units of capacitance, from which

c=J-<„

v cn

if v cn can be forced to unity, this reduces to
C= lt n

I is then scaled to yield C in units of time as pF, nF or uF

Example 1.

64 Microcomputing, October 1979

*<b

CONSTANT

CURRENT

SOURCE

V cn ■£»'

Fig. la. Capacitor charging
from a constant current source
results in a linear voltage that
is proportional to current and
time.

three functions of the circuit as
precision current sources, ca-
pacitor charge/discharge con-
trol, low-high limit detection.

Precision Current Sources

There are two current source
circuits: The first supplies one
of four switch-selected capaci-
tor-charging currents; the sec-
ond establishes the reference
voltages for limit detection. The
Motorola IN 4565 is a tempera-
ture-compensated reference di-
ode, specified for a tempera-
ture coefficient of .01 %/ °C drift
at a diode current of 500 ^A.
CR1 is a diode-connected tran-
sistor. Its function is to track
the base-emitter diode of tran-
sistor Q1.

In constructing the circuit, I
first assembled the current
sources and made a prelimi-
nary adjustment of the current
for each switch setting. A final
adjustment must be made when
assembly is completed. I used
a four-position DIP switch for
range selection. I used style
RV6, 1/2 Watt, single-turn com-
position potentiometers with
good results. I used them be-
cause I have a number on hand;
if I were to buy a new one, I
would purchase a cermet trim-
mer, such as the Beckman se-
ries 66. 1 used carbon resistors,
but for best long-term stability,
metal or cermet film would be
preferable.

Leakage current measure-
ments of the transistor diodes
should be made to ensure good
devices. Leakage should be
about 10 to 20 nA. I made all
measurements with a Keithly
model 179, 4V2 digit DVM. Since
Q2 operates at a relatively large
current, a 6.2 volt zener and
IN914 compensating diode are
a satisfactory reference, as-
suming room temperature use.

♦ V

Fig. 1b. Addition of a shorting
switch and comparator with a
reference input provides a step
output at time that is propor-
tional to the value of C.

Fig. 1c. Two comparators in a
low-high limit detection circuit
eliminate error due to switch
offset.

Fig. Id. Timing diagram for the
low-high limit comparator cir-
cuit.

30 -

o i

0 I

Fig. 1e. Exclusive OR gate and
logic table.

Capacitor Charge/

Discharge Control

Capacitor charging is con-
trolled by transistor Q3. This
switch has two functions: to
discharge the capacitor at the
end of the charging cycle and
to limit the maximum voltage
across Cx to about 2.5 volts.

The cycle is controlled by the
counter reset pulse. You may
wonder why a flip-flop is in the
circuit. It takes a certain length
of time for Cx to discharge.
Large capacitors, and electro-

lytics in particular, require a
longer time to discharge than is
available between counting in-
tervals. The 4013 sets and re-
sets Q3 through the LM339 for
alternate charge and discharge
sequences. The LM339 assures
adequate drive for the transis-
tor.

Though measurements are
made at alternate counting in-
tervals, two sets of data will ap-
pear on the display. This is be-
cause discharging the capaci-
tor yields a pulse that is also
measured. There is no confu-
sion between the two; the value
measured is large compared to
the discharge time. For many
small capacitors the discharge
time will read zero.

Low-High Limit Detection

The primary problem I en-
countered with this circuit was
oscillation of the low-limit com-
parator. The oscillation occurs
because the input is a slowly
rising ramp. The conventional
technique for handlingthis isto
provide hysteresis with positive
feedback from a resistor to the
-i- input. This approach cannot
be used because the feedback
current is then summed into the
charging current. A 10M resis-
tor will contribute about 1 pA of
current, which is unacceptable.

Since I could not eliminate
the oscillation, I decided to use
it to my advantage. The capaci-
tor voltage builds up with time
until it is equal to the voltage
across R20, about 750 mV. The
comparator output then jumps
from low to high. That is what
we want, but unfortunately it
doesn’t stay there. Various fac-
tors cause the output to jump
back and forth until the rising
input passes through the tran-
sition region, allowing the out-
put to stabilize in the high state.

The network of C3, CR6 and
R23 conducts the initial output
rise around to the + input to
force a small rise in voltage,
sufficient to maintain the high
output state. The diode forces
the capacitor to discharge
through the 1M resistor. The
long discharge provides time
for the input to rise sufficiently
to maintain the output.

A clean leading edge of the
output pulse is essential. KIM-

CTR captures the first pulse it
sees; if that is a 3 pS spike, that
is what you read. I read a lot of
them before I solved the prob-
lem. The solution has been very
effective.

The network is not needed on
the high-limit comparator. KIM-
CTR will detect the first transi-
tion and stop the count. Output
pull-up resistors R21 and R22
are both bypassed for equal re-
set times.

R19and R20should be metal-
film resistors for low-noise and
long-term stability. The abso-
lute values are not critical be-
cause the 1.000 voltage across
R19 must be obtained by an ad-
justment of R10 when the cir-
cuit is fully assembled.

Measurement Accuracy

Two factors affect the achiev-
able measurement accuracy.
One is internal, that is, the ac-
curacy with which the current
sources are adjusted and their
stability, both long and short
term. The other is external in
that capacitor leakage will dis-
tort the measurement.

The LM339 inputs contribute
a bias current that sums in with
the charging current. You can
measure this current by simply
connecting your multimeter
across the Cx terminals with
the four DIP switches open. I
measured 115 nA. Fortunately,
this current is nearly constant,
with a positive temperature co-
efficient (doubles each 10 °C
rise in temperature).

To perform the final current
source adjustment, leave the
meter across the Cx terminals
and adjust R2, R4, R6and R8for
a precise 1, 10, 100 and 1000 pA,

1 o*V cc

Vr 'a \ R E

Fig. 2. Single transistor con-
stant current source. For a
given value of V R , the collector
current is determined by the re-
sistance R e .

Microcomputing, October 1979 65

PRECISION CURRENT SOURCES

IpA

10 p A

NOTE ' TRIM RIO FOR
I.OOOV ACROSS RI9. A2
MUST BE IN CIRCUIT

CHARACTER CHARGE / DISCHARGE CONTROL

LOW- HIGH LIMIT DETECT

Fig. 3. The complete circuit schematic of the capacitance meter.

respectively. Close only one
switch at a time; do not sum the
sources.

With some experience you
can calibrate the comparator
bias current for the measure-
ment of small capacitances. In
theory you can measure a 1 pF
capacitor with the 1 n A current.
In practice I found 10 pF to be
the minimum. However, you can
still measure a 1 pF capacitor

with a simple trick.

I stripped two conductors
from a 10-conductor ribbon ca-
ble, terminated one end with
mini clips and then clipped bits
off the other end until it mea-
sured 10 pF. With this calibrat-
ed test lead I can measure any
value of small capacitance. I
connected a 115 pF mica ca-
pacitor and left KIMCTR run-
ning for five days of continuous

measurement. From time to
time, I looked at the display.

I had performed the final cali-
bration adjustments on one of
our typically balmy La Jolla
days when my home lab was
close to 70 °. During the five-day
period the temperature in-
creased. I observed a positive
temperature coefficient of
about 1/3 pF/°F. The maximum
I observed in the display during

the five days was 118 pF. It
never dropped below 115 pF.

Capacitor leakage lengthens
the measurement time; the ca-
pacitor looks larger than it really
is. For this reason measure-
ments should be made at the
highest feasible current. I use
four digits as a target; the 4th
digit typically shows some jitter.
With careful adjustment of the
current sources, you should
achieve measurement consis-
tency of 3 percent or better be-
tween ranges with low leakage
capacitors. Absolute accuracy
of better than 5 percent should
be achievable. Generally speak-
ing, all types except ceramic
disks and aluminum electrolyt-
ics are measurable with fairly
decent accuracy.

An assortment of readings
from mylar and mica capaci-
tors showed a scatter ranging
from right on to about ±3 per-
cent. If you want to look at the
capacitor charging ramp with
your scope, be sure to use a X10
probe.

Overall, I am pleased with the
KIMCTR capacitance meter. I
consider it a real bargain in
terms of value per dollar of cost
and the effort to put it together.
I’ll get a lot of good use from it. I
think you will too.B

Reference

C. S. Pepper, “Measure Capaci-
tance Quick and Easy with this
Low-Cost Circuit,” EDN Maga-
zine, February 5, 1979, p. 130.

hivil

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1 No. Hollywood, Ca, 91605

(213)

787-3334

corporation

Tits K»,AI»m:,S 100 Users.

We have a quality hard copy printer
for your computer.

Control Data Model CAI34-A printer-terminal has:
1 32 print positions, solid characters (64 ASCII char.);
adjustable tractor feed; 30 CPS; and uses parallel I/O
port (Centronics Interface).

These terminals also have ASCII keyboard with 1 0 key
pad. Price $650.00; includes stand, covers and main-
tenance manual. 30 day warranty. FOB

6502 ~ US€RS

If you haven't been receiving "6502 USER NOTES,"
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Dynamic Ram card (using 41 1 6's) that can be built for
around $200 and used on most any 6502 system, a
pulse-type telephone dialer interface, a HEXPAWN
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65XX disassembler, a KIM/S-100 bus interface, two
oscilloscope interfaces, a couple of calculator inter-
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speed cassette software, several debug routines, nu-
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KIM, SYM, AIM and OSI users.

We're the original publication dedicated entirely to
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Subscription rates for Volume 3 which includes
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66 Microcomputing, October 1979

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KILOBAUD MICROCOMPUTING
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kibbaud microcomputing

articles you may have missed

during 1977 :

January 1977*

February 1977 ■

□ZAP'

□Chasing Those Naughty Bits
□Why So Many Computer languages?

□ The Remarkable Apple Computer

□ Beware the Wumpus
□Chase!

□Will the Z-80 Crush All Competitors?

□ Practical Microcomputer Programming Part 2 Oper-
ating Systems

□ The Trouble with Mass Storage Systems
□A Useful Loan Payment Program

□ Submarine! a game for the SR-52

□The Hobbyist's Operating System Part 2 Interfacing
with the Monitor

□ Found A Use for Your Computer! . a clock program for
the KIM

□ Sophisticating a Surplus Keyboard

□ At the Races

□RCA Tries Again with the 7 802
□8080 vs 370

□Cut 6800 Programming Time with this Extraordinary Pro
gram

□7 x 9 = 56

□ Learning Computerese

□ How to WIN the Surplus Came
□Making Money Is Nice

□The 8080 You May Have Missed

□ The "Kill a Byte"' Standard

□ A 6800 Single Stepper
□Computerized Statements

March 1977

□ Practical Microcomputer Programming Part 3: Soft-
ware Tools

□ The Motorola Way! . review of the MEK6800D1

□ Let's Hear It for the 680b!

□ The Paper Tape Caper
□Computers for Free!

□A New Approach to the 6800 the Astral 2000

□ journey into the CPU
□Only Five Senses

□ Floppy Disks
□The lupiter II

□ How to Win S25.000 of Your Own Money Keno game
program

□ Using the "$50" Terminal

□External Mass Storage Part 2: Digital and Audio Cas-
sette Systems

□Make Your 680b Smarter . a cheap memory expander
□Stop Bugs Now!

□Clocked Logic Part 7. The D Type and IK Flip-flops

□ The Cory Details of Cassette Storage
□The Fun of Learning BASIC

□ Super-Tube . tazzing up the Digital Croup TVT

April 1977

□ interrupts Exposed using microprocessor interrupt
capability effectively

□Clocked Logic . Part 2. Some Basic Applications

□ Build an Eight Channel Multiplexer for Your Scope

□ Sorting Routines

□ Number Rounding Program
□Meet the Tarbell/KC Interface

□ Super-Tester a digital design aid

□The Hobbyist's Operating System Part 3. Command
Language Processing
□The Slow-Stepping Debugger

□ BASIC-The Easy Way

□Now You Can Use Software Timing Loops

□ KIM-1 Memory Expansion

□ Heavy Duty Power Supply

□ Digital Audio

□ HILO

□ interfacing the Analog World

□ Everything about Semiconductor Memory

□ Three-State Logic explanation of a key microprocessor
element

□ Automatic Memory Dumper utility dump program for
6 800 users

riHangmath! . . . a new puzzlc/game

□ Now— BASIC for the 8008 — Even!

□ Microprogramming an insight into microprocessor de-
sign

□Computerized Babysitter

May 1977

□Clocked Logic Part 3 Data Converters and Special
Functions

□Cure Those End-of-Month Blues with a sales analysis
program

□Make Your Investment Count the inside view of a
custom MP-88

□ Speed Up Your 6800

□Who’s Afraid of RS-232 data communications explained'

□ Is it High? — or Low? understanding logic design con-
ventions

□ Know Thyself’ . confessions of a kit-builder

□ Protyping Systems Exposed’ a revealing look at the In-

tercept lr

□ interrupts Exposed Part 2 Implementing an Interrupt

driven System

□ Digital Audio Part 2 Generating that Weird Music

□ Now It's Imsai BASIC!

□ Bridging the Cap tips on turning an application into a

program

□Adding "Plop" to Your System a noisemaker for com-
puter games

□ Lunar Lander

□Silence Noisy Teletype Motors Part 7 Getting the Ball
Rolling

□A Home Computer Pioneer profile of Don Tarbell

June 1977

□ Build Your Own Interface
□Computer Club Promotional Techniques
□Artillery Practice

□ Put a Micro in Your School
□Torpedoes Away!

□ Build a Pulse Generator
□A TVT For Your KIM

□The BYTEDESTROYER review of an EPROM eraser

□ BASIC Timing Comparisons

□ Solving Keyboard Interface Problems
□A Clean Cassette

□Try a Design Console. . for practical hardware proto-
typing

□Try Solar Energy

□Simplified Billing System in BASIC for the small
business

□Kilobaud Klassroom No. 2 Cates and Flip-flops Ex-
plained

□Computerized Typesetting an introduction to word pro-
cessing

□introducing! The World's Cheapest Computer a $60
SC/MP

□My Friend is a Computer lunkie

July 1977

□ inside the Sphere Microcontroller
□The Great TV to CRT Monitor Conversion
□Computer Turns Director . . an interview with filmmaker

lohn Whitney

□The Random Number Came

□Cassette Interface First Aid . use your processor to set
timing

□ Understand Your Computer's Language

□Kilobaud Klassroom . No. 3: IK Flip-Flops and Clock
Logic

□ Digital Audio Part 3: Signal Expansion and Compression

□ It Was Great! . reviewing The First West Coast
Computer Faire

□ Pass the Buck computer decision-maker program

□ Inside the Amazing ASR 33 checking out the most
popular terminal

□ Try Computer Composition

August 1977-

□Cassette I/O Format

□Expand Your SWTP 6800 with a new 8K board

□ Trigger Your Oscilloscope
□Sobriety Tester Program

□ Random Integer Program
□Test ICs With Your Micro

□ Heavy Duty Altair Power Supply

□ Is the KIM-1 For Every-1?

□ Electronic Design by Computer

□ Understand Your Computer's Language Part 2 Instruc-
tion Sets

□ Enter the Audible Computer!

□Time Bomb Came

□Try a Do-All Program!

□Sooo, You Want to be an Author!

□SWTP 4K BASIC Notes implementing it on the 6 80b

[ JHexdec hexadecimal to decimal conversion
l IStart a One-Man Computer Club

□ Troubleshoot Your Software a trace program for the
6502

f JCure that Hot Power Supply

September 1977

□ Build Your Own ASCII Keyboard with serial and
parallel output

t )The Ultimate Personal Computer

□ Talk Your Computer's Language’

[ )A PET For Every Home a look at the Commodore Pt T
2007

□Kilobaud Klassroom No 4 PC boards and power sup-
plies

t ]Seals E let tronirs

□ Try an 8080 Simulator

□ Build a $20 EPROM Programmer tor the ‘>402 4K chip

□ Faster MIKBUC Load Technique uses binary format

□Decoding Device Control Codes uses a UAR T. naturally

□ Tarbell Asynchronous Format
[ I Baseball in BASIC

[ JUsmg an Invisible PROM how to relocate monitor pro-
grams

t iKlingon Capture Came
! ^Starting a Business?

October 1977 —

□ BASIC Timing Comparisons

□Learn and Earn BASIC and business programming

□ Bargain Time’

□ Hello’ Today s Program Is understanding computer
speech recognition

□ Beware the Altair Bus

□ Put Your Imsai on the Rack’

□ 3D Computer Craphics
□Memory Troubleshooting Techniques

□ Understand Your Interrupts' real time clock appli-
cations

□ Kilobaud Klassroom No 5 hardware logical functions

□ Digital Croup MAXI-Basic

□ Utilize ASCII Control Codes'

□Dedicated Controllers

□ Try WORDMATH'

□ Time for Timesharing?

□ Build a Universal I/O Board for your Altair

November 1977

□ Everything about Assemblers' sure beats hand-coding

□ Your Image Counts'

□Lifetime Program

□Consider a MITE Printer alternative to theASR-33

□ Tired of Substituting Chips?

□ Stretch Those Characters mods for the SWTP PR-40
□Magnetic Bubble Memory

□ Reliable Conversion Techniques
□Salesmanship. Hardware and Coffee

□ Hyper about Slow Load Times? KIM Hypertape is an
alternative

□ interested in Commercial Programming?

□Kilobaud Klassroom No 6. voltage, current and power
supplies

□Expand Your KIM' with Altair bus devices

□ Enhance Your Memory with home information retrieval

□ Build the $35 Modem uses the MC14412 and a UART
□Another Look at Benchmark Program

□ Son of Submarine Came

□ Payroll Program for small businessmen

□ SC/MP Coes Baudot add an inexpensive TTY

December 1977— -

□ TVT Hardware Design Part 7. instruction decoder and
scan

□Expand Your KIM' Part 2 getting to the nuts and bolts

□ Payroll Program (Continued) cassette techniques
□The Business Market

□ALL CAPS

□The "Learning Machine" math tutor program
□Kilobaud Klassroom No. 7. transistors, diodes and op
amps

□Compleat Guide to Logic Diagrams
□Tiny BASIC

□ The Twelve Days of Christmas

□Paper Tape It's Here to Stay a look at the OP BOA
□Tempus Fugit
□Who Needs a Broker?

□ Here's HUEY! super calculator for the 65 02
□Crash Landing! a real-time Lunar Lander game
□File Structures Simplified

issues not available

kibbcud microcomputing

articles you may have missed
during ’78 & ’79

/January 1978 September 1978

□ Business Applications

□ Growing with KIM expansion PC board

□ Has Godbout Done It Againf . Econoram II: $ 150
assembled

□ The TRS-80: how does it stack up?

□A Tale of Four BASICs

□ Hardware Program Relocation

□ TVT Hardware Design

□ Understanding Loaders

□ Kilobaud Klassroom . No. 8: pulses — and more pulses

□ Help for Beginning Programmers

□ Your Imsai and You

□ Rocket Pilot . . . an interactive game for the Apple-ll

□ Micro Maestro

□ Software Keyboard Interface

□ Morrow's I/O Cassette Board

□ It's Your Hobby!

February 1978*

March 1978

□ Build the "Simple Computer" a home-brew 8080

□ Hardware Program Relocation, Part 2

□ State Capitals

□ Customized MIKBUG
□TV Typewriter Update

□ Foolproof Cassette Operation

□ Number-Crunching Time

□ Super Terminal! interfacing the Burroughs 9350-2

□ Consumer Computer, Inc.

□ Programmed Instruction Made Easy: Tiny PILOT, Part 1

□ Protect Your Memory Against Power Failure

□ Backup Techniques . how fail-safe is your system?

□ Small Business Software, Part 2

□ Expand Your KIM! . . . Part 4: a TTY substitute

□ Faster Erase Times . . build a quicker EPROM eraser

□ l/O Programming for the Altair Disks

□ The Axiom EX-800

□ Tiger Trouble! .7/ programmable-calculator safari

□ Temperature Sensing

□ A Different Approach to HI-LO

April 1978*

May 1978*

June 1978*

July 1978

□ Two Hobbies: Model Railroading and Computing

□ Revolving Charge Account Calculations

□ A Tour of the Faire, Part 2

□ Taming the I/O Selectric . . Part 2: software

□ Heath's Experimenter's Breadboard

□ Draw Dazzling Color Graphics . . . routines for Cromem-
co's Dazzler

□ Atwood Memory for Your KIM

□ MIKBUG with Muscle!

□ Little Bits . . strings , statements, routines
□Cook's Memory Test .for the 8080
□An S-100 Front Panel Replacement

□ Home-Brew Z-80 System . Part 2: CPU and memory
board

□ Battleship!

□ improvements Make the Difference . . SWTP's new sys-
tem

□ Simple and Low-Cost PROM Programmer

□ Compatibility and the Altair Bus

□ Retail Pricing System

August 1978

□ DOCUFORM: A Word-Processing System for Everyone!

□ Kilobaud Klassroom . No. 77. Data and Address Buses

□ Software Debugging for Beginners

□ Mils vs North Star

□ Kansas City Standard . . . at 7200 baud

□ Swords and Sorcery!

□Two Hobbies: Model Railroading and Computing, Part 2

□ Update: Lunar Lander

□ The Do-It-Yourself System . Heath’s H8 is a winner!

□ KIM + Chess = Microchess

□ is There Intelligent Life in Your Computer Room?

□ From Base to Base . with your HP 25

□ FINANC: A Home/Small-Business Financial Package

□ Computer-Generated Signs

□ Copying Computer Cassettes

□ Something Extra With Radio Shack's BASIC

□ The Amazing 1802

□ Who Needs a UART?

□ Can't Find It? . . . an index for your SW7P BASIC manual

1 J(Con)text Editor

□At Last: A Client Timekeeping System

□ Troubleshooters' Guide

□ Metric-American Conversion Program

□ The Heath/DEC Connection Part 1: overview

□ Home System Demo Program

□ Do-lt-All Expansion Board for KIM

□ Tally Ho! fox and hounds game

□ Baudot Interface Cookbook

□ Error-Correcting Techniques
UKIM Organ

□ Kilobaud Klassroom . No. 72. ROM and RAM mem-
ories

□ Motorola's Latest: The MC6802
LTRS-80 Update: Level II BASIC
L Super Cheap 2708 Programmer

□ Something Extra in Mass Storage Meca’s Alpha-1

□ From Big BASIC to Tiny BASIC

October 1978

□ Budget System KIM, keyboard, TV, TVT-6L and AKIM
t JThe Heath/DEC Connection Part 2: Hll system periph-
erals

□ Depreciation Calculations

□ Looping in Tiny BASIC

□ Kilobaud Klassroom . No. 13: I/O Circuitry
ULet Your Computer Wear a Watch

□ Randomness is Wonderful

□ Dazzler and BASIC

□ The Latest in Operating Systems for the 6800: FLEX

□ Action on the Enterprise

□ Will DEC and IBM Be the Final Winners?

□ Little Bits

□ View from the Far East

□ Use That Parity Line!

□ The Software Patchcord

□ A Useful Address List Program

□ Ready for the Nuthouse?

□ Build a One-Chip Single Stepper for the 6502

November 1978*

December 1978

UDura/ltel Selectric for Low-Cost Hard Copy

□ A "Gift" That Keeps on Giving

UThe Art of Generating Expense Reports
UDeep, Dark Secrets of the TRS-80 (Level I)

□ Interfacing the Elf II

□ The Care and Feeding of Cassette Tapes, Part 1

□ Kilobaud Klassroom . No. 15: computer I/O III

□ Raster Scan Graphics for the 6800 Part 2: the software

□ SWTP 4K RAM Write Protect Option
□TSC Text Editor

□ Spelling Bee

□ Two Interface Boards from Teletek

□ Attention, Chess Buffs!

□ The Ups and Downs of Business

□ BASIC Control of Servomechanisms

□ There Is a Better MIKBUG!

□ How to Write Good Application Programs

□ Sharing Scheme for RS-232 Channels

□ Scratched Diskette?

January 1979

□ An Editor for 6800 BASIC Programs

□ u-Panel for KIM

□ Rolling Dice

□ Pseudo Graphics

□ The BCS and Its President

□ Address List Editor

□ Display Your PET!

□ TRS-80 Tape Controller

□ SHHH — People Are Sleeping

□ Say It with a Banner

□ Open House

□ Cassette Interfacing

□ PET Techniques Explained

□ A Service Bureau for Hobbyists

□ Little Bits

□ Keeping Ma Bell Happy

February 1979

□ Block-Structured Language for Microcomputers

□ Kilobaud Klassroom, No 16: I/O IV

□ Computerized Climate Control

□ Music, Maestro!

□ Madam Dupre's House of the Zodiac

□ Disk Power!

□ Inventory Control with the TRS 80

□ Onward with the COSMAC Elf!

□ Build a $50 TVT!

□ Percom's LFD-400 Floppy Disk System

□ DOTS

U The Apple Speaks — Softly
U Super Mastermind

□ TRS-80 Level II Reference Manual Index

□ Care and Feeding of Cassette Tapes (Part 2)

□ Text/Document Preparation Made Easy

□ Simpler Interest

□ Learn BASIC — with BASIC

□ Use Flowcharts to Communicate
U Joystick Interface for Your Altair
U Attack on the Pack!

March 1979

U Cheap Video for Your Heathkit H8

□ Analog and Digital Interfaces

□ The "El Cheapo" EPROM Programmer

□ Is Your Video Monitor Dangerous?

□ Thoughts on the SWTP Computer System

□ PET User Port Cookbook

□ Chess Pawn

□ Home Computer Exterior Ballistics

□ Heath H9 Page Erase

□ The SKIP II Microcomputer

□ Ultra Banner

□ Teletype's KSR-43

□ The One Percent Forecasting Method

□ Too Many Variables?

□ Kilobaud Klassroom No 17: I/O V

□ The Electric Pencil

□ How to Talk to Your 8080

□ Programming the 1802

□ Keyboard Interrupt for the TRS-80

□ The OS I Model 500

□ Sleep Better with a Microcomputer

□ Telpar Thermal Printer

April 1979

LJ A Look at TRS-80 Peripherals
U Heath H8 Disk System

□ DOTS (Part 2)

□ Truly Random Numbers

□ SWTP CT -1024 Mod

□ Who Sells Software?

□ How Important Is Projjer Termination?

□ How to Talk to Your 8080 (Part 2)

□ Parallel Port to RS-232— Inexpensively

□ Free Speech Lessons for the TRS-80

□ Let's Go Flying

□ Floppy Disk System from Tarbell

□ The Wait State Explained

□ Depreciation Analysis

□ Twin Cassettes for Your TRS-80

□ Bar-Graph Generator

□ Let's Have Some Order

□ Quicksort!

□ Put Something Super in Your Life

□ Starship Attack

□ Terminate Your Troubles

□ Testing PET Search Algorithms

□ Two Diamonds

□ How about a Printer?

□ A Look inside the TRS-80

May 1979

U A Text Formatter in BASIC

□ KIMCTR

□ High-Speed Cassette Interface

□ How to Talk to Your 8080 (Part 3)

□ Data Base Management

□ Analog and Digital Interfaces (Part 2)

□ COSMAC Double Play

□ COSMAC Double Play (cont.)

□ From Microcomputer to Micro-Piano

□ A Game of Darts

□ Prettyprinting with Microsoft BASIC

□ Kilobaud Klassroom No 18

□ MDOS

□ A TRS-80 Cross-Index

□ Graphing with the TRS-80

□ An All-in-One Interface

June 1979-

□ "Monitor"

□ TRS-80/Selectric Word Processor

□ Thoughts on the SWTP Computer System (2)

□ New Life for Our Altair

□ TVBUC

□ Creative Tabulation

□ A Handle on Programming

□ Keepbook

□ Vector Graphing Techniques

U Putting the 1802 on the S-100 Bus

□ A Personal Finance System (Part 1)

□ Building a New Horizon

□ Microcomputers and TVI

□ Translating Between TTL and RS-232 Levels

. . . and more!

issues not available.

Get a Software Discount!

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BUSINESS PACKAGE I Keep the books for a small
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• Detail Input— This program lets you create and record
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• Month and Year to Date Merge— This program will
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• Profit and Loss— With this program you can quickly
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• Year End Balance— This program will combine all
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With this package, you can make your TRS-80 a working
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Doodles and Displays I 16K Order No. 0030R.

Space Trek III 4K; Order No. 0031 R.

Fun Package I 16K; Order No. 0037R.

Hex Pawn/Shuttle Craft Docking/Space Chase/ Sea Battle
16K; Order No. 004 1R.

BUSINESS PACKAGE III This package can change your
TRS-80 into a full working partner for any businessman.

• Inventory— Maintain a computer based inventory for a
constant inventory system.

• Discount and Commission Percentages— Let your
computer figure out mark up and discount calculations,
sales tax and more. This is a perfect time saving package
for any small business.

For the TRS-80 Level I 4K. Order No. 0061 R

Level I and II

Basic and Intermediate Lunar Lander

4K; LI, 16K L.II; Order No. 0001 R.

Space Trek II 4K LI, 16K L. II; Order No. 0002R.
Backgammon and Keno 4K LI, 16K L II; Order No. 0004R.
Ham Package I 4K LI, 16K L.II; Order No. 0007R.
Electronics I 4K L.l, 16K L.II; Order No. 0008R.
Golf/Crossout 4K L.l, 16K L.II; Order No. 0009R.

Air Flight Simulation 4K LI, 16K L.II; Order No. 0017R.
Oil Tycoon 4K L.l, and Lll; Order No. 0023R.

Bowling 4K L.l, 16K L.II; Order No. 0033R.

SANTA PARAVIA AND FIUMACCIO The year is AD 1400,
and you are the ruler of a tiny Italian city-state. You are
ambitious by nature and intend to build your little city-
state into a powerful kingdom.

So begins Santa Paravia and Fiumaccio, where you
and your fellow players compete as rulers of neighboring
cities. You control the grain harvest, feed your people,
set tax rates, exercise justice, invest in public works and,
of course, try to stay on the good side of the church.

Life was short back then, and you'll have only a
limited amount of time in which to build your kingdom.
The lives of your serfs will depend on your decisions. If
they are wise, then your city-state will grow and you will
acquire loftier titles. If your rule is incompetent, your
people will starve and your city-state may be invaded by
your neighbors.

You can play the game yourself, or set up the tourna-
ment version, which allows up to six players at a time to
compete. Either way, you’re sure to find your route to the
throne a challenging and rocky road.

How will you rule your kingdom? Will you be a
benevolent ruler— an iron fist in a velvet glove— or will
you become unscrupulous and follow the example set by
Niccolo Machiavolli in his book on government, The
Prince ? Only you can answer that question— with Santa
Paravia and Fiumaccio. Order No. 0043R

All Packages $7.95 except where otherwise indicated.

Level II

Model Rocket Analyzer and Pre-Flight Check

16K; Order No. 0024R.

RAMROM PATROL

The Ramrom probe
ships are steadily ad-
vancing. You’ve only a
limited amount of
power, and you’re a
long way from home,
but as a member of
the Ramrom Patrol,
your mission is clear.

Destroy the Ramrom
probes at any cost.

Manage your ship effi-
ciently and effectively,
and you just might
complete your mis-
sion and still have
enough fuel to reach
your base. If, on the
other hand, your "shot” leaves something to be desired,
you're sure to wind up in the hands of the dreaded
Ramromians— whoever they are. But don't worry— get-
ting there is all the fun!

• Klingon Capture— Your mission is to capture a
Klingon battle cruiser intact— no mean feat by anyone’s
standards. In fact, the only known way to bring it home
alive is to destroy any stars that happen to surround the
cruiser, thereby rendering it incapable of moving. But
don't expect the cruiser to sit in one place and allow
itself to be caught. You’ll have to keep a watchful eye on
your screen for the scanner reports and keep your fingers
crossed.

• Tie Fighter— The object of the game, in this simula-
tion of a battle between an X-wing and Tie fighters is to
shoot down as many of the enemy as possible within the
allotted 200 time units. You fly the X-wing fighter and, if
you aim carefully and shoot quickly, who knows . . . you
just might wind up as the next hero of the revolution— or
at least your living room! Order No. 0028R

TRS-80 UTILITY II The second in a series of programs
designed to help the programmer, Utility II will add un-
precedented flexibility to your BASIC programs, by
allowing you to combine them with other BASIC pro-
grams or with machine-language programs or routines.

• CFETCH— After you have renumbered your programs
using RENUM (see Utility I) you can use the CFETCH pro-
gram to merge your consecutively numbered BASIC pro-
grams. CFETCH also allows you to search a program for
its file name, without merging It with the resident BASIC
program.

• CWRITE— This powerful program allows you to merge
one or more machine-language programs with other
machine-language programs or with a BASIC program.
Merged programs can then be loaded with a single com-
mand. CWRITE also makes it possible for you to obtain a
general checksum (impossible to do when CLOADing a
BASIC program) and also allows you to load programs in
non-consecutive locations within the memory.

Order No. 0076R

TRS-80 UTILITY I

Tired of having your
best programming
efforts frustrated by
the lack of tools?

These two powerful
TRS-80 utility pro-
grams should be
stock equipment in
every programmer’s
"toolbox."

• RENUM — Never
again will you have
to leave out that new
routine or feature
because you lack
available line num-
bers. RENUM will re-
number your Level I
or Level II programs by whatever increments you
specify— including all GOTOs and GOSUBs!

• DUPLIK— One of the first laws of computer program-
ming is to retain duplicate copies of all of your programs.
With DUPLIK, you'll be able to make and/or compare
copies of BASIC, source assembler, and machine-lan-
guage programs. If you have more than one program on a
cassette, DUPLIK will enable you to load and save them
all by using a single command— without merging. And
all of the above can be performed on your Level I casset
tes while you’re using your Level II machine!

Order No. 0081 R

Space Trek IV 16K; Order No. 0034R.

Doodles and Displays II 16K; Order No. 0O42R.

Bowling League Statistics System
16K; Order No. 0056R. $24.95
Cards 16K; Order No. 0063R.

Teacher 16K; Order No. 0065R. $9.95
Household Accountant 16K; Order No. 0069R.

Financial Assistant 16K; Order No. 0072R.

PET**

Personal Weight Control/Biorhythms 8K; Order No. 0005P.

MORTGAGE WITH PREPAYMENT OPTION/FINANCIER

These two programs will more than pay for themselves if
you mortgage a home or make investments:

• Mortgage with Prepayment Option— Calculate mort-
gage payment schedules and save money with prepay-
ments.

• Financier— Calculate which investment will pay you
the most, figure annual depreciation, and compute the
cost of borrowing, easily and quickly.

All you need to become a financial wizard with an 8K
PET. Order No. 0006P

Casino I 8K; Order No. 0014P.

Casino II 8K; Order No. 0015P.
Checkers/Baccarat 8K Order No. 0022P.

Dow

0026P Copyfighl 1978, Intttnt Sottwv* me 91978

DOW JONES Up to six players can enjoy this exciting
stock market game. You can buy and sell stock in
response to changing market conditions. Get a taste of
what playing the market is all about. Requires a PET with

8K. Order No. 0026P

Tangle/Supertrap 8K, Order No. 0029P.

Trek-X 8K; Order No. 0032P.

Qubic-4/Go-Moku 8K; Order No. 0038P.

— — — — MIMIC — ■

How good is your memory? You can find out with the
Mimic program, and for a fraction of the price of similar
games being offered on the market today.

Your PET will flash a sequenceof figures on the screen
and ask you to repeat them in the same order. It may
sound easy, but there are five different programs, one of
which is sure to keep you going until you're ready to
throw in the towel. It’s fun, it’s bound to improve your
memory, and it’s even programmed for optional sound ef-
fects; all you need is an amplifier and a speaker.

Order No. 0039P

Penny Arcade 8K; Order No. 0044P.

Arcade II 8K; Order No. 0045P.

Baseball Manager 8K; Order No. 0062P. $14.95.

Dungeon of Death 8K; Order No. 0064P.

Arcade I 8K; Order No. 0074P.

Digital Clock 8K; Order No. 0083P.

Turf and Target 8K; Order No. 0097P.

*A trademark of Tandy Corporation

* *A trademark of Commodore Business Machines Inc.

***A trademark of Apple Computer Inc.

Now you can get the best for less! Just clip out the coupon below, bring it to your
local computer store, and you’ll get $1.00 off the list price of any program package
from Instant Software!

Apple***

Golf Applesoft II + 20K Order No. 001 8A.
Bowling/Trilogy 20K; Order No. 0040A.

MATH TUTOR I The Math Tutor I package is designed to
help younger children learn the concepts of mathe-
matics. It uses the technique of positive, immediate rein-
forcement. When the child enters a correct answer, he or
she is rewarded with the opportunity to move a space-
ship, cast a magic spell, or rescue a man from a most un-
fortunate fate. By using this method of positive rein-
forcement, children will learn to associate mathematics

with pleasant experiences, as opposed to the stark reali-
ty of numbers that has driven so many pupils to an early
dislike of math. The program also provides the opportuni-
ty for parents to indulge in a unique learning experience
with their children, while introducing them to the ex-
citing world of microcomputing. Teachers can also use
the program in a classroom setting to provide that extra
incentive. Math Tutor I contains the following programs:

• Hanging— A variation of the traditional game of Hang-
man. In Hanging, students must spare the graphic
character’s “life” by correctly answering the questions
posed by the computer.

• Spellbinder— The student is cast as a magician com-
peting against another magician who’s controlled by the
computer. He must answer the questions about frac-

tions correctly in order to cast magic clouds, fireballs,
and other spells at his rival.

• Whole Space— Students are given the opportunity to
lead an attack on an evil planet. Every time a correct
answer is given to a math problem posed by the com-
puter, he can move his ship closer to his goal. Every
wrong answer gives the enemy an opportunity to fire
back.

Note: the Hanging program requires Applesoft II BASIC.
The Whole Space and Spellbinder programs can run in in-
teger BASIC. Order No. 0073A

Math Tutor II Applesoft II + 20K Order No. 0098A.

Dealer Inquiries Invited

Ask for Instant Software at a computer store near you.

Alabama

The Computer Shack

913 Shadyview Lane, Adamsville

Computerland of Huntsville
3020 University Or. Huntsville

Mittets TV & Radio
621 East Broadway. Mesa

California

Byte Shop of Mt. View

1063 West El Camino Real, Mt. View

Byte Shop of Sacramento
6041 Greenback Ln. Citrus Heights

Capital Computer Systems
3396 El Camino Ave. Sacramento

Computer Components of South Bay
15818 Hawthorne Blvd. Lawndale

Computer Components Inc

6791 Westminster Ave. Westminster

Computerland

16720 S. Hawthorne. Lawndale

Computerland of San Francisco
117 Fremont St. San Francisco

Computerland of W. LA
6840 La Cienga Blvd. Englewood

Microsun Computer Center
2989 North Main St. Walnut Creek

Opamp/Technical Books

1033 N. Sycamore Ave. Los Angeles

Radio Shack

8250 Mira Mesa Blvd San Diego

Silver Spur Elect. Comm.

13552 Central Ave. Chino

The Computer Store

820 Broadway, Santa Monica

Colorado

Byte Shop

3464 S. Acoma St. Englewood

Connecticut

Bridgeport Computers Inc.

3876 Main St. Bridgeport

The Computer Store

43 South Main St., Windsor Locks

D.C.

Computer Cablevision
2617 42nd St. NW. Wash. DC

Florida

AMF Electronics
11146 N. 30th St. Tampa

Computer Center

6578 Central Ave., St. Petersburg

Computerland of Ft. Lauderdale
3963 N. Federal Hwy., Ft. Lauderdale

Heath Kit Electronic

4705 W 16th Ave. Center. Hialeah

Sound Ideas

2201-C N.W. 13th Gainesville

Georgia

Atlanta Computer Mart
Atlanta

Hawaii

Computerland of Hawaii
567 N Federal Hwy.

Radio Shack

1712 S. King St. Honolulu

Illinois

Computer Station

3659 Nameoki Rd. Granite City

Midwest Micro Computers, Inc.
708 S. Main St., Lombard

Louisiana

Computer Shoppe Inc.

3225 Danny Park Suite 222,
Metairie

Maryland

The Comm Center
9624 Ft Meade Rd. Laurel

Massachusetts

Computer Packages Unlimited
99 Reservoir St. Holden

The Computer Store

120 Cambridge St. Burlington

Tufts Radio & Electronics
206 Mystic Ave. Medford

Michigan

Computerland of Grand Rapids
2927 28th St. S.E. Kentwood

Computerland of Rochester
301 S. Livernois Rochester

Computerland of Southfield
29673 Northwestern Hwy. Southfield

Computer Mart

560 W. 14 Mile Rd. Clawson

Hobby House

1035 W. Territorial Rd. Battle Creek

Nebraska

Omaha Computer Store
4540 S. 84th St. Omaha

New Jersey

Radio Shack/J&J Electronic
Mansfield Shopping Ctr. Hackettstown

New Mexico

South West Computer Center
121 Wyatt Drive, Suite 7. Las Cruces

New York

Aristo Craft
314 Fifth Ave. NYC

Computer Corner

200 Hamilton Ave. White Plains

Computer Factory
485 Lexington Ave. NYC

Key Electronics
Schenectady

Ohio

Astro Video Electronics
504 E. Main St. Lancaster

Computer Store of Toledo
18 Hlllwyck Dr. Toledo

Make a great buy even better . . .

21st Century Shop
16 Convention Way, Cincinnati

Oregon

Computerland of Portland
12020 SW Main St. Tigard

Pennsylvania

Artco Elect.

302 Wyoming Ave. Kingston

Erie Computer Co.

1253 West 8th St., Erie

Personal Computer Corp.

Frazer Mall, Lancaster Ave. Frazer

South Carolina

Seely Communications
1084 Broad St., Sumter

Tennessee

Computerlab

671 S. Menden Hall Rd. Memphis

Texas

Computercraft Inc.

3211 Fondren, Houston

Computer Port

926 N. Coll ig, Arlington

Interactive Computers
7620 Dashwood Rd. Houston

K.A. Elect.

1220 Majesty Dr. Dallas

Ram Micro Systems

6353 Camp Bowie Blvd. Ft. Worth

Virginia

Home Computer Center

2927 Virginia Beach Blvd. Virginia Beach

Washington

Personal Computers
S 104 Freva, Spokane

Ye Old Computer Shop
1301 G. Washington, Richland

Wisconsin

Byte Shop Of Milwaukee
6019 West Layton Ave. Greenfield

Wyoming

Computer Concepts
617 W I6the St., Cheyenne

Canada

Compumart

Station J. Ottawa, Ontario

Computer Mart. Ltd.

1055 Yonge St. Suite 208 Toronto

Micro Shack of W. Canada
333 Park Street, Regina. Sask.

Orthon Holdings Ltd.

12411 Stony Plain Road
Edmonton, Alberta

Total Computer Systems
Ajax, Ontario

West Germany

Reinhard Nedela
Markstr. 3. 7778 Markdorf

Name

Why pay full price? Take this coupon to the store nearest you and get $1.00
off on any of our software. If the store nearest you doesn’t stock Instant
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Instant Software Inc. Dept. 69JO
Peterborough, N.H. 03458 USA

More TRS-80 Horsepower-

adding 16 K of memory and
“Level III” BASIC

Save money on your memory upgrade, and get Level I and Level II in the same machine.

Ronald W. Cowart
3603 Burgundy
Houston TX 77023

Y our TRS-80 microcomputer
displayed the word SORRY
all too often as you were enter-
ing the last part of a BASIC pro-
gram into its 4K memory (SOR-
RY indicates that no more
memory is available). So you
deleted all the REMARK state-

ments, used all possible abbre-
viations and finally got the pro-
gram to fit into the 4K memory
space.

Being only human, you im-
mediately found errors in the
program as you tried to RUN it.
Then you were faced with the

W L

Photo 1. Component side of the computer PC board. The locations of ROM, RAM and the two DIP
switches are shown.

formidable task of debugging a
faulty BASIC program full of co-
lons and abbreviations with no
helpful REM statements. (Ra-
dio Shack Level I BASIC allows
the user to pack multiple state-
ments onto one line if colons
are used between statements.
Additionally, commands such
as PRINT, FOR and GOTO can
be abbreviated as P., F. and G.,
respectively; the LET command
can be omitted completely.)

If you haven’t experienced
this scenario, you soon will.
The easiest solution to this
problem is to increase the
memory capacity of your ma-
chine to 16K of RAM (random
access memory). You can take
your computer-keyboard as-
sembly to the nearest Radio
Shack store, which will make
this expansion for you at just
under $300, or you can do it
yourself for under $100. This ar-
ticle will give you instructions
for the do-it-yourself technique.

Introduction

If you were lucky enough to
get your 4K program function-
ing, you probably ran into more
trouble down the road if you
had your 4K machine converted
to Level II BASIC. As Level II
programs are recorded onto
cassette at a higher baud rate,
all of your Level I program
tapes must be converted to the
faster Level II. When Radio

72 Microcomputing, October 1979

Photo 2. Keyboard and subassembly. The correct placement of the Level II ROM board is illustrated.

Shack installs Level II BASIC in
your machine, they supply cas-
sette tapes that will perform
this job. However, the programs
on these cassettes take up
some memory space and make
it impossible to convert your
longer programs to run on your
Level II machine.

Radio Shack recommends
the installation of 16K of mem-
ory to solve this problem. I rec-
ommend installing both Level I
and Level II BASIC in your ma-
chine. That’s right, use the Lev-
el I BASIC ROM (read only mem-
ory) with Level I tapes and
switch to Level II BASIC ROMs
for Level II tapes. You will find
this a convenient means of re-
taining long Level I programs
that would not run on your Lev-
el II machine because of mem-
ory requirements for tape con-
version.

The second part of this arti-
cle deals with the installation
of Level II BASIC and the sim-
ple modifications required to
retain the Level I ROM. You
realize, of course, that these
modifications give you “Level
III” BASIC. Doesn’t Level 1 +
Level 11 = Level III?

Installation of 16K RAM

The 16K memory-expansion
technique is simple. The only
tools required are a small flat-
bladed screwdriver to be used
as an 1C (integrated circuit) re-
mover and a Phillips screwdriv-
er to open the case of the com-
puter-keyboard assembly. The
eight 16Kx8 bit memory chips
can be ordered from any one of
several suppliers who advertise
in the pages of Microcomput-
ing or from a local electronic
parts supplier. The memory
chips required are 4116 dynam-
ic RAMs. (I ordered mine from
Jade Computer Products and
got excellent service and chips
for the $85 cost.) Additionally,
two 16-pin programmable
shunts or DIP switches are
needed. The DIP switches are
preferred if you intend to install
Level II BASIC at a later date.

Before you install the 16K
memory, I should warn you that
the Radio Shack warranty on
your computer will be voided if
you even open the computer-
keyboard assembly. Since my

90-day warranty had already ex-
pired when I installed the 16K
memories, I was not too con-
cerned about this. You proba-
bly won’t be either.

When you have the eight
RAMs, two DIP switches and
two screwdrivers in hand, you
can begin the installation pro-
cedure, and in no more than 15
minutes, your computer will
have 16K of memory. Just fol-
low the steps outlined below.

1. Turn the computer-key-
board assembly upside down
and remove the six screws with
the Phillips screwdriver.

2. Turn the assembly right
side up and remove the top
cover from the keyboard.

3. Carefully lift the keyboard
from its five supports and let it
hinge toward you. While hold-
ing the keyboard in one hand,
remove the five white plastic
spacers, noting where they
were inserted.

4. Then remove the entire PC
(printed circuit) board assem-
bly and keyboard from the bot-
tom case and lay the PC board,
component side up, on a table
with the keyboard above it.

5. The 4K memory chips now
need to be removed from the PC
board. These chips are labeled
Z-13 through Z-20 on the PC
board. (Refer to Photo 1 for
their exact location.) Before re-
moving them, you should con-
nect a wire jumper from your
hand to ground to prevent

static electricity from possibly
damaging the chips as you
touch them. You should also
observe this technique for in-
stalling the new chips. To re-
move one of these chips, slip
the flat blade of the screwdriver
under one end of the chip and
pry it up slightly. Then, pry the
other end up slightly until the
chip can be removed. Be care-
ful as the pins can be bent easi-
ly. Remove the other seven
chips in the same manner. Save
these 4K chips as they can be
used in the expansion interface
that Radio Shack markets or
can be used in a memory inter-
face of your own design. Put
them in the container the new
chips were shipped in since it is
conductive and will protect
them.

6. Install the new 16K chips
by inserting them into the now
empty sockets. They need not
be placed in any particular
order. However, be careful to in-
stall the chips in the correct
orientation. Either a small
notch, dot or the numeral 1
should appear on the end of the
chip, which should be placed
toward the top of the board.

7. Remove the two DIP
shunts labeled Z-3 and Z-71 us-
ing the removal technique de-
scribed in step 5. The positions
of these shunts are also shown
in Photo 1. In this photo, the
new DIP switches are shown in-
stalled. I used nine switch DIPs

as I could not locate the eight
switch DIPs needed. Examine
Z-3 closely (in the top right of
Photo 1) and you will find that I
soldered the switches in back-
wards. Switch #1 should be
closest to the edge connector,
not switch #9. 1 managed to get
Z-71 in correctly (one out of two
is not bad). It is not necessary
to remove the sockets and sol-
der these switches to the board
as I have done. They can simply
be plugged into the empty sock-
ets. As you plug your switches
into the sockets at Z-3 and Z-71 ,
check that switch #1 is toward
the top of the board in both
cases. Then, program the
switches by referring to Fig. 1.
Notice that Level I machines
are programmed differently
than Level II machines.

8. Reassemble your comput-
er, plug in the power and turn
the unit on. Type “PRINT MEM.”
If you have a Level I machine,
the number 15,871 should be
printed. If yours is a Level II ma-
chine, the number 15,572 should
be printed. If the correct num-
ber is not displayed, recheck
the programmable DIPs for mis-
takes and try again. If the num-
ber is still wrong, the problem
could possibly be a bad mem-
ory chip.

Installation of Level II BASIC

The Level II BASIC kit must
be ordered from Radio Shack.
The kit contains a preassem-

Microcomputing, October 1979 73

DIP Pins

Switch

Level 1

Level II

Level III

Number

16K

Z71

1,16

0**

2,15

3,14

4,13

5,12

6,11

7,10

8,9

*C = Closed

**0 = Open

Fig. 1. Look under the column heading corresponding to your machine to find the correct switch positions for Z3 and Z71.

bled printed circuit board, rib-
bon cable, resistor, two cas-
settes and a Level II manual.
The cost of the kit includes in-
stallation by Radio Shack. They
will take your computer-key-
board assembly and install the
necessary parts. However,
when the unit is returned to
you, the ROM containing Level I
BASIC will be missing, and in
its place will be the Level II
ROMs. (If you are not interested
in having the Level III modifica-
tion, let Radio Shack do the in-
stallation.) If you want Level III
capability, you must install the
Level II kit.

Before ordering the kit, check
to make sure that you do not
have one of the early model
TRS-80s, as the Level III mod
cannot be made on these
models. This can be done by
disassembling your computer

as outlined in steps 1 through 4
of the 16K memory installation
procedure. Then check the
sockets labeled Z-33 and Z-34.
If both of these sockets contain
chips, you have an early model.

In these models, Level I BA-
SIC is installed on two ROMs. If
your unit contains two ROMs,
the installation procedure de-
scribed below will not apply.
The majority of TRS-80s have
only one ROM, either in socket
Z-33 or Z-34. This ROM should
be labeled BASIC I. The other
socket will be empty.

Follow the installation proce-
dure listed below for this type
of ROM configuration. Some
soldering and a few etch cuts
are required to install Level II.
You should have some experi-
ence with these techniques be-
fore attempting the conversion
to Level II.

1. Remove the top cover of
the computer-keyboard assem-
bly. You are now ready to at-
tach the 3-ROM printed circuit
board provided in the Level II
kit. Remove the protective
covering from the adhesive
backing on the small PC board.
Firmly press this board into
place beside the keyboard as-
sembly. A properly positioned
board is shown in Photo 2. The
plastic tubing containing four
colored wires should extend
out to the left alongside the
keyboard. The connection of
these four wires will be dis-
cussed later.

2. The 24-pin ribbon cable
extending down from the PC
board should be routed around
to the component side of the
computer board. Remove the
Level I BASIC ROM and plug
the ribbon cable connector into

its socket. Plug the Level I ROM
into the remaining empty sock-
et for the Level III option. Other-
wise, leave the socket empty.
Your board should now look as
pictured in Photo 1.

3. Now we turn to the con-
nection of the 4-wire cable.
Three of the wires are to be con-
nected to the computer ad-
dress bus, and the fourth wire
serves as an enable line for the
ROMs. The connection of these
wires is shown in Photo 3. Dis-
regard the three wires in the
right side of the photo, since
they are not needed in the Level
II installation but will be used
later for Level III. The yellow
wire should be connected to bit
A t1 on the address bus. This
can be accomplished by solder-
ing this wire to pin 13 of ICZ-38.
The red wire should be con-
nected to bit A 12 on the address

Photo 3. Backside (foil side) of the computer PC board. The con-
nections for Level II BASIC and the modifications for Level III are
pointed out.

Photo 4. Computer and subassembly. This close-up shows the
connection of the resistor supplied with the Level II kit which is
labeled R-1. Its value is 4.7k Ohms.

74 Microcomputing, October 1979

< ffwm mimi u

H,n.n iii w. w wm.mmm

****** to: *: m (*:x.xx m

* to to to to to to, to to. to. toWM to
to" to to to to i) to. to. to. to m tom

micro

COMPUTER

SYSTEM

Photo 5. Computer-keyboard case. The mounting of the Level I-
Level II switch is shown.

bus by soldering this wire to pin
5 of ICZ-38 or by following the
run from pin 5 of ICZ-38 up to-
ward the edge connector. You
will encounter a feedthrough in
the board near this connector,
and the wire can be attached at
that point. The orange wire
should be connected to bit A 13
of the address bus. This con-
nection can be made at pin 7 of
the ICZ-38 or again at a feed-
through on the path leading
from this pin to the edge con-
nector. The green wire is the
ROM enable line and can be left
unconnected for now if you in-
tend to have Level III capability.
If you are installing only Level
II, solder this wire to pin 6 of Z-3.
Z-3 is one of the DIP switches
and it will provide the enable
pulse for the ROMs.

4. The resistor provided in
the kit should now be con-
nected. Its proper location can
be seen in Photo 4. It is located
in the top-right corner of the
computer board. The purpose
of the resistor, apparently, is to
reduce the amplitude of the in-
coming cassette audio signal.

5. An etch cut should now be
made on the board as a safety
precaution. The location of the
etch cut is shown in Photo 3 in
the top-left corner. A jumper
from pin 39 to pin 38 of the edge
connector should be made.
These modifications are not
necessary, but keep more pow-
er from being drawn from the
board through the edge con-
nector. The power supply
should not be loaded further.
The + 5 volt pin on this connec-
tor is changed to a ground by

this modification.

6. If you are not concerned
with the addition of Level I BA-
SIC to your Level II machine,
your installation job is almost
complete. Program the DIP
switches Z-3 and Z-71 as shown
in Fig. 1. All that remains for
you is to reassemble the case
around your computer and plug
in the power and video cables.
When power is applied and the
video monitor displays MEM-
ORY SIZE, you are on your way
with Level II BASIC. Enjoy the
fruits of your labor.

Modifications for
Level III BASIC

Before continuing, check to
make sure that your Level I
ROM is plugged into socket
Z-34 and that socket Z-33 con-
tains the ribbon cable connec-
tor that leads to the Level II
ROM board. Also, the green
wire, which is the enable line
for the Level II ROM board,
should not have been con-
nected yet.

A double-pole, double-throw
switch will be needed to make
the modifications suggested.
Fig. 2 illustrates the connection
of the switch to a TRS-80 as out-
lined In the steps below. Num-
ber 26 insulated wire is recom-
mended for the jumpers, which
should be approximately 12
inches long to allow for proper
positioning of the switch.

1. Contacts 2 and 5 of the
switch are the swingers. Pin 2
should be connected by means
of a 12-inch jumper to the green
wire of the Level II ROM board.
As such, this contact serves as

Fig. 2. Switch connections for
LEVEL III option.

the enable for the Level II
ROMs. Contact 5 should be
connected to the backside of
the computer board at pin 20 of
either Z-33 or Z-34. This contact
serves as the enable for the
Level I ROM.

2. Contacts 3 and 6 of the
switch should be jumpered to-
gether with a short piece of
wire. Then a jumper from these
contacts to a source of +5
volts on the computer board
should be made. I made the + 5
volt connection at pin 16 of
Z-69. The jumper is actually
soldered to a feeder that runs
from this pin toward the bottom
of the board. This serves to
hold the enable line of the un-
used ROM in the inactive high
state, as the enable lines are
active low.

3. The two remaining con-
tacts, 1 and 4, should also be
jumpered together. Then, a
jumper from these pins to the
backside of the PC board should
be made. The connection point
is at a feedthrough located be-

low pin 20 of Z-34. The exact lo-
cation is Illustrated In Photo 3.
This is the chip enable sent
from the Z-80 microprocessor
to the BASIC ROMs.

4. Now make an etch cut just
above the feedthrough pin-
pointed in step 3. If this etch cut
is not made, the Level I ROM
will never be disabled.

5. Program the DIP switches
Z-3 and Z-71 as shown in Fig. 1
for Level III.

6. The only remaining task is
to mount the switch in the case
of the computer. I found the po-
sition shown in Photo 5 to be
very favorable. There is
enough room in this area of the
case to prevent the switch con-
tacts from touching any part of
the PC board. The job is com-
plete when you have finished
mounting the switch.

With the modifications de-
scribed in the previous steps,
Level I BASIC will be enabled
with the switch in one position,
and Level II BASIC will be func-
tional with the other position of
the switch. Don’t try to switch
from Level I to Level II or vice
versa while power is applied be-
cause errors will occur. I hope
you enjoy your Level III TRS-80
as much as I have enjoyed
mine.

Conclusion

In conclusion, I would like to
add a few tips on the use of a
cassette recorder with Level II
BASIC. The volume setting of

Photo 6. The Level II kit as supplied from Radio Shack. Also shown
is the double-pole, double-throw switch for Level III.

Microcomputing, October 1979 75

the recorder is much more criti-
cal than it was when using Lev-
el I BASIC due to the higher
baud rate. You can easily waste
an hour getting a cassette to
load in properly if the volume is

not adjusted properly. This is
especially true if you are using
a recorder other than the one
supplied by Radio Shack.

I have found it helpful to
place a radio near the comput-

er-keyboard assembly while
loading cassette tapes. Tune
the dial in between stations
(preferably using the AM band)
and start the cassette in mo-
tion with the CLOAD command.

Turn the volume control slowly
from low to high. You will notice
a high-frequency pulsing sound
become progessively clearer
and then fade out as the volume
is increased. Adjust the volume
dial for maximum clarity of this
sound and then reset your com-
puter. The cassette recorder
should now be close to the cor-
rect volume setting.

You can also use the radio
for unique sound effects. Write
a short BASIC program with
several different timing loops
incorporated using FOR-NEXT
statements. As the program is
executed the radio will pick up
various frequency signals gen-
erated on the computer board.
For different sounds, change
the length of thetiming loops or
tune the radio to a different fre-
quency.!

Acknowledgement

I would like to thank Jack
McCraw for the photography
and artwork appearing in this
article. Also, I would like to
thank Fran Gange for typing
the manuscript.

Photo 7. The author’s TRS-80 system.

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Probos V

Even in these inflationary times a logic probe for the cost of a fast-food lunch isn’t bad!

Steve Dominguez
29 Mines Park
Colorado School of Mines
Golden CO 80401

L ogic probes have been
around for a long time. Few
test instruments are as conve-
nient or easy to use for trouble-
shooting digital circuits as the
logic probe. With it, you can
quickly determine if your circuit
is functioning properly and rap-
idly isolate any problems that
occur.

Unfortunately, most com-
mercial probes cost more than
many of us can afford. When I
first became involved in digital
electronics, I did all of my trou-
bleshooting with an LED. But I
soon learned this wasn’t the
best way to search out logic
gremlins. And besides, I was
running out of LEDs; my evil
side, Dr. Diode, gets his kicks
plugging ’em into the wall sock-
ets and watching them blow
up!

Since I couldn’t afford a com-
mercial logic probe, I set out to
build one from scratch. Every
probe I had built from plans I
“ripped-off” the library had
some sort of fault. Either they
didn’t work right, didn’t do what
I wanted or else used some
weirdo part that was impossi-
ble to find. Finally, I remem-
bered what my father said to
me every time I loused up a job
he gave me: “The only way to
get something done right is to
do it yourself!” Thus, I designed
Probos V.

By now you’re probably grum-
bling to yourself, “Oh, no,
another one of those ‘Build a
Simple Logic Probe’ articles.”
Not so. If there is one thing I’m
fed up with, it’s a simple logic
probe.

My logic probe had to do at
least five things:

1. Indicate logic 0 states

2. Indicate logic 1 states

3. Indicate Tri-state outputs

4. Detect both positive and

Components needed for making Probos V. The PC board is
optional.

negative pulse transitions

5. Work with TTL and TTL-com-
patible circuits

I have yet to see a circuit that
meets all five of these require-
ments.

Probos V does all that I want
and then some. It performs as
well as many commercial probes
and doesn’t cost more than two
hamburgers, french fries and a
shake! You should be able to
build Probos V for under $5.00; I
built mine for $1.40!

Circuit Theory

The simplest of all logic
probes consists of merely an
LED connected between +5
volts and a test point as shown
in Fig. la. Unfortunately, most
TTL circuits don’t like this kind
of Rube Goldberg setup. Most
TTL circuits consider a logic 0
as any voltage below 0.8 volts
and a logic 1 as any voltage
above 2.4 volts. Generally
speaking, TTL gates can sink
up to 20 mA in their logic 0
states. This means the gate can
supply up to 20 mA of current
without causing its output volt-

PROBE

Tlp 220 £1

age to rise above 0.8 volts.

The same is essentially true
for gates in their logic 1 states.
If we tried to pull more than 20
mA from them, their output volt-
age would drop to about 1.7
volts, which is neither a logic 1
nor 0. As a result, we would dis-
able any gates connected to
the output since the output
voltage isn’t high enough to be
distinguished as a logic 1.

Since most LEDs require
about 20 mA, connecting them
directly to the output of a gate
in the test circuit can upset
even the parts of the circuit that
are working. While the LED will
probably light up, the gate’s
output voltage will enter a state
of limbo between 0.8 and 2.4
volts; consequently, any gate
connected to this output is dis-
abled, and the circuit malfunc-
tions. That’s bad— we certainly
don’t want a test instrument
that does that.

So what do we do? We can
put a current-limiting resistor in
series with the LED to cut its
current down to about 15 mA.
But this doesn’t solve anything

LED + 5V

♦5V

Fig. 1. Bare, minimum logic probe (a); improved second-genera-
tion logic probe (b).

78 Microcomputing, October 1979

if we are testing a gate that is
already sinking 12 mA, for ex-
ample. 15 mA -1-12 mA = 27 mA,
7 mA over the limit and bound
to create some problem. If we
further reduced the LED’s cur-
rent, we wouldn’t be able to see
it (now, what good is that?).

In addition to loading down
the test circuit, the LED logic
probe has two other problems.
First, it can detect only one log-
ic state and cannot distinguish
open circuits. Second, it cannot
detect pulses or pulse trains
over 25 Hz.

As you can see, an all-LED
logic probe is not a good idea.
However, we must still use the
LEDs to show the logic levels
without loading down the test
circuit. The solution is simple:
We can put a few inverters on
our logic probe to drive the
LEDs. Fig. 1b shows the sche-
matic for the second-genera-
tion logic probe.

Inverter A turns LED 1 on
when the probe tip touches a
logic 1 test point. This is be-
cause the LED lights only when
its cathode is connected to a
logic 0 output. The inverter in-
verts the 1 into a 0, and the LED
lights up.

Inverters B and C invert twice,
so LED 2 lights when the probe
tip touches a logic 0. Since in-
verters A and B require only 2
mA of input current each (4 mA
total), we can safely probe our
faulty circuits without fear of
loading them down. The invert-
ers themselves supply the 20
mA needed for each LED. In ef-
fect, the inverters do two things:
(1) drive the LEDs and (2) dis-
tinguish between high and low
logic states.

While the second-generation
probe is significantly better
than the LED probe, it still has a
few problems. The circuit still
cannot tell the difference be-
tween logic 1 and floating in-
puts. That is, LED 1 will light if
the probe tip contacts a logic 1
output or if it touches a discon-
nected output. While this is nor-
mal for TTL logic, it certainly is
not desirable for a test instru-
ment. And like the first LED log-
ic probe, our second-genera-
tion model cannot detect
pulses.

Probos V completely elimi-

Probos V completely assembled.

nates these two problems. The
complete schematic for Probos
V is shown in Fig. 2. As you can
see, it is an overhauled version
of our second-generation probe.
R1 , R2 and Q1 have been added
to force a logic 0 into inverter A
when the probe tip touches an
open circuit. Now the HI LED
(L2) turns on only when the
probe tip touches a logic 1 out-
put. Otherwise, it remains dark,
as does the LO LED (LI). Now
our logic probe can distinguish
between high, low, floating and
Tri-state (which is essentially
the same as a floating output)
outputs.

But our problem is still not
solved. We now need a way of
detecting pulses. Fortunately
for us, there is an 1C that will do
this. It is called a monostable
multivibrator, or, simply, a one-
shot. The one-shot is a special-
purpose flip-flop with a resistor
and a capacitor connected to it.

When the one-shot detects a
pulse on its clock input, its out-
put changes from Q to Q. Simul-
taneously, the capacitor is
charged. Regardless of how
long the pulse stays in its logic
0 or 1 state, the capacitor im-
mediately begins to discharge
via the resistor. Once it has
discharged, the one-shot’s out-
puts change from Q back to Q.

By varying the RC time con-
stant of the resistor and capaci-
tor (T = RxC), we can change
the amount of time the Q out-
put is on. Probos V has a time
constant of about .3 seconds
(0.3 sec = 15kx22uF).

I used the 74122 one-shot for
the simple reason that I didn’t
have any others I could use.
The 74122 is triggered by apply-

C1— 22 uF, 16 volt tantalum capacitor
C2— 4.7 uF, 16 volt tantalum capacitor
D1,D2 — 1N4148 (or 1N914) signal diode
L1-L3— Light emitting diode (see text)

IC1— SN74122N monostable multivibrator
IC2— SN7404N hex inverter
Q1— 2N2222 NPN transistor
All resistors 1/4W, 5%:

R1— 2k
R2-390 Ohm
R3,R4,R6— 180 Ohm
R5— 15k

Misc.: Printed circuit board, probe tip, hookup wire, alligator clips, 1C sockets,
solder, etc.

Parts list.

Fig. 2. Complete schematic for Probos V.

Microcomputing, October 1979 79

Probos V in action troubleshooting another one of the author’s
bum circuits! Note that the logic probe is powered by the circuit
being tested.

PROBOS 3Z

Fig. 5. Probe tip can be installed inside a pen case and wired to
Probos V as shown.

ing a logic 0 on its clock input.
Hence, it would detect only
negative (HI to LO) pulse transi-
tions. No good! I wanted a logic
probe that would indicate posi-
tive (LO to HI) as well as nega-
tive pulse transitions. Fortu-
nately, the inverter section of
Probos V lends itself quite nice-
ly to solving this problem.

As you will recall, the HI and
LO LEDs light only when their
cathodes are at a logic low. The
two LEDs, however, indicate
different logic states. By ORing
the one-shot’s clock input with
the outputs of inverters A and C
we get a logic 0 pulse on the
clock whenever the probe tip
contacts a high or low logic
level.

At last the problem is solved.
Since the 74122 has an OR gate
built right into it, we don’t need
to add another 1C. By connect-
ing an LED to the one-shot’s Q
output, we have a way of indi-
cating the presence of a pulse.
If a pulse only 100 nanosec-
onds wide whisked by the
probe tip, we would never notice
it if we observed only the HI and
LO LEDs. They would change
states too fast to notice. But
the one-shot catches the pulse
and turns on the PULSE LED
(L3) for 0.3 seconds, indicating
the presence of a pulse.

We now have a logic probe
that can differentiate between
logic levels, open circuits and
pulses of both the positive and
negative variety. It doesn’t re-

quire many parts or cost a sul-
tan’s fortune. What more could
you ask for?

Construction

Probos V can be constructed
in any manner you choose.
Since I wasn’t concerned about
cramming everything inside a
bail-point pen (after all, the
commercial probes aren’t), I
built mine on a printed circuit
board. The etching and drilling
guide for the PC board is in Fig.
3.

Once you have made the PC
board, solder in the resistors.
The parts placement guide in
Fig. 4 shows where the parts
are to be mounted. Next, solder

in the diodes (watch polarity!)
and the jumper wire. Now in-
stall the transistor and the ICs,
paying particular attention to
their orientation. Then solder in
the two capacitors, once again
being careful of polarity. I spec-
ified tantalum capacitors in the
schematic and parts list only
because they are much more
compact. If you wish to econ-
omize, you can use less costly
electrolytic capacitors without
sacrificing circuit perfor-
mance.

Next install the LEDs. Be
sure they stick up above every-
thing else if you plan to mount
Probos V in a case. I’m quite
fond of pretty lights so I used a
different-color LED for each
logic state. You may want to do
the same.

Once you have all the parts
mounted on the PC board, at-
tach a probe tip and the power
leads. For the probe tip, I used
an ordinary straight pin. The

sharp point is good for piercing
solder masks as well as your-
self, so you may prefer to use a
less pointed probe tip, such as
a small finishing nail. You might
also want to mount the probe
tip in a pen by itself and con-
nect it to Probos V via a piece of
wire as depicted in Fig. 5.

The power leads are easier to
connect to a power supply if
you attach alligator or, better
yet, 1C test clips to the ends of
them. Color coding the wires
(red for Vcc, black for GND)
helps prevent hooking them up
backwards.

Checkout

Probos V is powered by the
circuit under test. Connect the
Vcc lead tothe +5 volt terminal
and the ground lead to the
ground terminal of a dc power
supply. When the power is
turned on, the PULSE LED will
light momentarily. The other two
LEDs should remain dark.

Fig. 3. Full-size etching and drilling guide for printed circuit board.

Fig. 4. Parts placement guide for Probos V’s PC board. Watch orientation of capacitors and semicon-
ductors.

80 Microcomputing, October 1979

LOGIC I

HI LED ON

HI LED

LO LED

PULSE LED

Condition Indicated

OFF

Insufficient or no Vcc, no contact, floating
or high impedance (Tri-state) input.

LOGIC 0

OFF

Logic 1 state.

OFF

Logic 0 state.

OFF

Positive pulse transition.

LOGIC 1

OFF*

Narrow negative pulse or pulse train.

OFF

Negative pulse transition.

LOGIC 0

OFF*

Narrow positive pulse or pulse train.

Pulse train with fairly even duty-cycle. At
low frequencies LEDs will blink on and off;
at higher frequencies, they will appear to be
continually lit.

LOGIC 1

OFF OFF

*Weak or dim LED
"Blinking LED

ON**

Fluctuating or unstable Vcc.

LOGIC 0

Table 1. Conditions that can be indicated by Probos V.

LOGIC 0

-y HI LED ON -j—

PULSE
LED BLINKS
DURING PULSE
TRANSITIONS

HI LED DOES NOT RESPOND
TO NARROW PULSES

LO LEO ON

PULSE LED BLINKS DURING PULSE TRANSITIONS

Fig. 6. Various waveforms and indications detectable with Probos
V.

Touch the probe tip to ground.
The PULSE LED should blink,
and the LO LED should now be
lit.

Now touch the probe tip to
+ 5 volts and observe that the
PULSE LED will blink again.
The HI LED should now be lit
(the LO LED should have turned
off as soon as you removed the
probe tip from ground). If the
probe appears to be malfunc-
tioning, check to see that it is
properly hooked up to a work-
ing, filtered, 5 volt dc power
supply. If it is, kill the power
and check the probe for miss-
ing parts, cold solder joints,
broken or shorted wires (or PC
board foil traces), defective
components and improperly in-
stalled parts.

Usage

If everything goes as it is

supposed to, Probos V will be
complete. If you are industri-
ous, you may want to put it in-
side a case. I didn’t bother to
build a case.

Table 1 and Fig. 6 show the
various conditions Probos V
can indicate. As you can see,
Probos V can detect many con-
ditions in the test circuit.

To use Probos V, simply con-
nect the Vcc and ground leads
to the Vcc and ground in the cir-
cuit you are testing. Touch the
probe tip to any point in the cir-
cuit to see what’s happening
there.

A few words of caution: Do
not use Probos V to trouble-
shoot circuits whose Vcc is
greater than 5 volts. Also, I
don’t recommend using Probos
V on MOS or CMOS circuits
that are not TTL compatible or
have been buffered with a 4049

1C, for example.

As a final note, you may wish
to build Probos V with a dual
one-shot 1C such as the 74123.
The second one-shot could be
used as a pulse injector that is
triggered by a push-button
switch. You could also use a
555 timer as a pulse train (sig-
nal) injector. This would make it
easier to test flip-flops, count-
ers, etc., since you could inject
a pulse into them to advance
them into a new state.

Since Probos V is inexpen-
sive to build, you could build
several of them for a super data

bus or 1C monitor. Just be care-
ful you don’t add so many that
power requirements become a
problem. Each logic probe re-
quires about 40 mA.

Conclusion

Probos V is an amazingly ver-
satile instrument capable of
checking out the operation of
TTL, RTL, DTL and some CMOS
circuits. And Probos V is ex-
tremely cost effective, perform-
ing as well, if not better, than
commercial probes costing ten
times as much. Is this the ulti-
mate logic probe? I hope not! ■

TRS-80

REAL ESTATE APPRAISAL
AND

ANALYSIS

—Mortgages

Present + Future Value
— Ellwood Analysis
—Capitalization
. . . others

$49.95 complete
LEVEL || — 4K

Sand for Free Softaara Info Packet.
• 0-Disk System Only • TD-Taee or Disk Laval II •

Compress - IT .? $ 24.95

2 Programs i Ramova Spaces & REM statements. Compraasas
program into max multiple statement lines. Reduce RAN
needs up to 50j(.

Simplify -IT.? $24.95

3 Programs: Lists in single statement lines. Searches &

Finds requested text or key comnands. Lists all variables
used in program.

TEXT.? *49.95

A Combination Text Processor A ELECTRIC FILING CABINET.
WRITE EDIT FILE Reports, Information files: auto Directory,
DISK store nith auto Backup options. File searches by
Title or Content on 1 to 4 Disk Drives. Formats A Prints.

A SELF INDEXING QUERY SYSTEN and Word Processor.

List’n File: Names & Things ?. $34.95

Create and maintain NANE (customer) files. Sort using
any information category. Print lists or labels.

All progress supplied on TAPE or DATA DISKETTE
Indicate your preference end RAN sire.

VISA'

Bluebird's Inc.

"J 144-1 Greenview Ave.
East Lansing. Mi. 48823

Nlchigan residents add sales tax.

TRS-80’

SOFTWARE

Send for Fr66 Software Info Packet.
• D-Disk System Only * TO-Tspe or Disk Level II •

Math / Stat Pac *39.95

7 Programs: Linear, multiple, polynomial, geometrical,

exponential regression analyses. Simultaneous aquations,
Bargraph with auto axis. Plot any polynomial over any
range (Reduce or Enlarge) with auto axis.

DISK. 0 *14.95

The HOW TO rudements of your Disk System. Interactive
with lots of dynamic examples. Helps a beginner use
the disk system.

Hangman/ Hangfile , T .? $19.95

2 Programs: Educational. Create your omn dynamic

word files. User option multiple clues A subjects
with graphics. Really FUN.

Secret Words -Game!?. $17.95

3 Programs i Educational A Fun A Nind Boggling. Guess

a 2, 3, 4,5 letter word. Revise A Status options. 3
Versions: Easiest gives lots of clues. Hardest no

° U **’ All programs supplied on TAPE or DATA DISKCTTE
Indicate your preference end RAN size.

Bluebird's Inc.

1441 Greenview Ave.

East Lansing. Mi. 48823 ^ B50

Michigan residents add 4% sales tax.

iS Reader Service— see page 227

Microcomputing, October 1979 81

PET’s Keyboard Grows Up

Owners of older PETs have suffered with their Munchkin-size keyboards long enough.

can be seen in the photograph):

1. The SHIFT keys on both
sides have been moved up a row
to their normal positions, one
row above the space bar.

2. The OFF RVS key has been
moved up two rows, where a
typewriter SHIFT LOCK key
would normally be found.

3. With the SHIFT and OFF
RVS keys moved up, a standard,
full-size space bar was used.

4. An extra row of keys was
added on the right side of the
numeric pad to provide addi-
tional SHIFT, RETURN, SPACE
and ? keys, which facilitate pro-
gram debugging, editing, nu-
meric calculations while in im-
mediate mode, etc.

5. A blank, unused switch that
may be wired however desired
was added on the top row. This
switch can easily be used to add
a system reset key to the PET,
and there is even a way to add
an electrical interlock for a reset
key to provide safety against ac-
cidental resets.

Mechanically, the keyboard
appears to be rugged, even
though an enclosure was not
available when I received my
unit. All the switches are
mounted on a metal plate with a
single printed circuit board pro-
viding all the switch intercon-
nections. The keytops are two-
shot, molded plastic with white
lettering and graphic charac-
ters, so there shouldn’t be any
problem with wear. All the func-
tion, cursor control and editing
keys are blue, while the majority
of the keytops are gray.

Connection to the PET is
through a single ribbon cable

Robert W. Baker
15 Windsor Drive
A too NJ 08004

S ince Commodore first intro-
duced the PET, everyone
has complained about the small
keyboard. Some owners have
added their own full-size key-
board, while others “just made
do” or simply bought another
computer system altogether.
After using my PET for about a
year, I finally decided I really

liked the system, but I had put
up with the small keyboard long
enough, and it was time to do
something about it. The painted
metal keytop inserts were start-
ing to show signs of wear, and
the larger RETURN and SPACE
keys did not always register,
depending on where they were
pressed.

While looking over the small
number of replacement key-
boards and ASCII keyboard
interfaces available for the PET,
I came across a new unit being
manufactured by Maxi Switch

for Century Research & Market-
ing of Minneapolis. Once I re-
ceived more information about
their design and found the price
was $109.95, I simply had to try
one on my system as soon as
possible.

Keyboard Features

This is the first replacement
keyboard with PET graphic char-
acters actually molded into the
keytops. The key layout is
almost identical to the original
PET design with several small
changes and improvements (as

Maxi Switch’s full-size replacement keyboard for the PET.

82 Microcomputing, October 1979

that replaces the cable from the
PET keyboard. Since the key-
board is a simple, direct switch
matrix, there are no fancy inter-
face boards with ROM decod-
ers, and there is no logic hard-
ware involved. I have not had
one problem with bounce, dou-
ble characters, missing key hits,
etc., in the four weeks I’ve been
using my new keyboard.

Connections

To attach the new keyboard,
simply unplug the old keyboard
and plug in the cable from the
new keyboard. The connector
from the new unit is currently
not a stacking-type connector,
so the PET keyboard must be
completely disconnected. Some
replacement keyboards do pro-
vide the ability to use both
keyboards simultaneously, but
the graphic characters are not
indicated, and several special
functions may not be available
on their keyboards (or may only
be available through specific
combinations of keys).

Once you’ve connected the
Maxi Switch keyboard, you’ll

forget all about using the orig-
inal keyboard. I’ve even been
thinking of removing the old key-
board from my PET and mount-
ing a panel for switches, dis-
plays, a speaker, etc.

To use the available blank
switch as a system reset switch,
connect the switch between
pins A27 (RES) and B27 (GND)
on the memory expansion con-
nector. Whenever you press the
new reset switch, the screen will
flicker for a few seconds while
the system is reinitialized, then
the normal messages displayed
at power-on will reappear. If
you’re worried about accidental-
ly pressing the reset switch
while typing on the keyboard
and losing your entire program,
fear not, for there is a solution.

Each of the RETURN keys on
the new keyboard has a double-
width keytop, and there are two
switches under each. Both
switches are used under the nor-
mal RETURN key, but only one is
used on the new key added to
the numeric pad. To provide an
electrical interlock for the reset
switch, just wire the unused

switch under the extra RETURN
key in series with the blank
switch. Now, you must press
both switches simultaneously
to generate a system reset.
Pressing the extra RETURN key
alone still produces a RETURN
function, while pressing the
reset switch (the blank switch)
alone will have no effect.

Conclusion

Having already used the PET
keyboard arrangement for some
time, I quickly became familiar
with the slightly new format.
Key positioning is still not iden-
tical to a typewriter, but the only
major difference is having to use
the numeric pad instead of the
top row of keys for numbers.
Also, the semicolon and colon
are still on separate keys, and
the period is only present in the
numeric pad. These differences
have not proven to be of any dis-
advantage for me personally,
but this would be a matter of
personal preference.

The “feel” of the keyboard
switches is comfortable, similar
to using a Selectric typewriter.

The difference in size and the
“feel” of the keys is significant
for me after using the original
Commodore keyboard for so
long. How did I ever put up with
that “toy” keyboard for so long?
Even Commodore is now offer-
ing a full-size keyboard in the
newer PET models, but, after
seeing the original keyboard, I
wonder how good they’ll really
be.

Cost of the new keyboard is
only $109.95 plus $5 shipping,
but this does not include an en-
closure for the keyboard, which
is available for an additional
$25.

For anyone interested in
ordering a keyboard for his sys-
tem or sending for more infor-
mation, he cannot deal directly
with Maxi Switch. All correspon-
dence should be addressed to:
Century Research & Marketing,
4815 W. 77th Street, Minne-
apolis MN 55435. In Europe, you
can contact the following for
pricing/availability: Erhargt &
Jost Electronic, Rossligasse 2,
CH-4450 Sissach, Switzer-
land. ■

Business Programs for the PET

Dr. Daley continues to expand software for the PET. Some of our newest offer-
ings for the businessman are listed below.

These programs are available NOW for the COMPU/THINK disk and will be
converted to the COMMODORE disk as soon as one can be obtained. All come with
documentation.

Inventory

This program will maintain a complete inventory for
the small business. Functions include entering and
editing of the new inventory, modifying individual
records, and a variety of reports $99.95

Estimate

This set of four programs will build a file for use, in
conjunction with one version of the above inventory

files, to prepare accurate estimates for an individual
job. This program can eliminate the difficulties and
inaccuracies of quote preparation $99.95

Mail List

This program will maintain a mailing list of about
6000 names kept in zip code sequence. Individual
records are accessed in seconds, and the entire list or
any subset may be printed on labels $99.95

Your order will be shipped within four business days from receipt.

Charge your order to
MC/V1SA

^D43 DR. DALEY, 425 Grove Avenue, Berrien Springs, Michigan 49103

Phone (616) 471-5514 Sun. thru Thurs., noon to 9 p.m. eastern time.

v 0 Reader Service— see page 227

Microcomputing, October 1979 83

Hurricane!

Hurricane season isn’t over. If you are unfortunate enough to live in a hurricane-prone area,
here’s a program that will enable you to monitor the next big storm that blows your way.

Bryce Segar

130 H. L. Sudduth Drive

Panama City FL 32401

W hether you live in an area
vulnerable to hurricanes
or not, it is interesting, and
many times vital, to be able to
monitor the hurricanes that oc-
cur each year. Using the pro-
gram in this article, you can
monitor a hurricane’s status in
comparison to your location or
any location you choose. In ad-
dition, while it is impossible to
consistently predict the path of
a raging hurricane with any de-
gree of accuracy, it is possible,
using your computer, to accu-
rately track the hurricane and
make straight-line path predic-
tions.

What the Program Does

The program is written in
Level II 16K BASIC for the TRS-
80 computer. It will provide you
with an accurate monitoring ca-
pability. Using the latitude and
longitude of your location as its
base and inputting the latitude
and longitude along with the
speed and direction of the hur-
ricane being tracked (normally
available through the National
Weather Service), the program
will determine the hurricane’s
precise degree of angle (in de-
grees from true North), as com-
pared to your location. In addi-
tion, it will compute the dis-
tance in miles between your lo-
cation and the hurricane.

The program will also tell you
whether the hurricane is Cur-
rently headed in your direction.
If the hurricane is traveling in a

straight line toward your loca-
tion, the program will output a
hurricane warning and a hurri-
cane condition status number
(using the hurricane categories
established by the National
Weather Service). It will also
predict the number of hours be-

fore the storm hits your area.

How the Program Works

Program lines 6 through 82
initialize the Hurricane pro-
gram and provide the input
statements that set up the vari-
ables. When entering the de-

grees of latitude and longitude,
do not enter the minutes or sec-
onds. You must first convert
them to decimals by dividing
them each by 60 and then add-
ing them on to the whole degree
number.

The critical element of the

Program listing.

1 REM * * * HURRICANE LOCATION AND DISTANCE CALCULATOR * * *

2 REM WRITTEN BY BRYCE D. SEGAR

3 REM PROGRAM RUNS IN TRS-80 LEVEL II - 16K!

4 REM SEE TEXT* TO RUN HURRICANE PROGRAM IN - 4K!

5 REM <<<<<<<< INITIALIZE PROGRAM

6 CLEAR 100 : CLS : PR I NTQ384, :G0SUB6000 : F0RTT-1T02 000: NEXT

7 CLS : PR I NT :GOSUB6 0U0 : PR I NT: INPUT"ENTER NAME OF YOUR LOCAT I ON"; I I $

8 PRINT: INPUT"ENTER YOUR LATITUDE IN DEG REES"; A: PRINT: I NPUT" ENTER YOUR LONGITUDE IN DEGREES";G
10 CLS : PR I NT :G0SUB6 000 : PR I NT

35 I NPUT"WHAT IS THE NAME OF THE HURR I CANE"; AS : PR I NT

45 PR I NT" I NPUT LATITUDE OF HURRICANE ";A$;" IN DEGREES"; : I NPUTB : PR I NT
70 PR I NT" I NPUT LONGITUDE OF HURRICANE ";A$;" IN DEGREES"; : I NPUTH

80 PRI NT: PR I NT"WHAT IS ";A$;"'S CURRENT DIRECTION OF TRAVEL (IN DEGREES)"; : I NPUTDD

82 PR I NT: PR I NT"WHAT IS ";A$;"'S CURRENT SPEED (MPH )"; : I NPUTSS

90 REM <<<<<<<< CALCULATE LOCATIONS AND DISTANCE

98 CLS : I FA-B AND G-H THEN H-H+.l

100 PRINT :GOSUB6000 : I -G-H:L"I

110 I F( I <180)AND( I >-180)GOT02 00

120 J-l *360:L-J

130 IF(J<180)AND(J>-180 )G0T02 00
140 L- I -360

200 I FL>0R-1

201 IFL<0R-0

204 E-S I N(A*. 0174533) :F-S I N(B* .0174533) :K-C0S( A*. 0174533)

230 M-C0S(B*. 0174533 ):N«C0S(L*. 0174533) :D=(E*F)+(K*M*N)

310 0«( -ATN ( D/SQR( -D*D* 1))* 1. 5708 )*57. 29578
320 P-SIN(0*. 0174533): Q-(F-(E*D))/(K*P)

350 C- I NT((-ATN(Q/SQR<-Q*Q*1))+1. 5708 )*57. 29578)

360 IFR-0C-360-C
400 QQ-(E“(F*D))/(M*P)

410 CC- I NT((-ATN(QQ/SQR(-QQ*QQ*1))*1. 5708 )*57. 29578 )

435 IFR-1CC-360-CC

470 0-0*6 0*1. 15078 :D- 1 NT(D* . 5 ) : PR I NT

480 REM <<<<<<<< DETERMINE DIRECTION

550 I FC>-0ANDC< 15THENGS -"NORTH" :GOT06 00

558 I FC>*15ANDC<75THENG$ -"NORTHEAST" :G0T06 00

560 IFC>»75ANDC<105THENGS* M EAST":GOT0600

563 I FC>*105ANDC< 16 5TH ENGS -"SOUTHEAST" : GOTO 6 00

565 I FC>-165ANDC< 195THENGS -"SOUTH" :GOT0600

568 I FC>® 19 5ANDC< 2 55THENGS-" SOUTHWEST" :G0T06 00

570 I FC>«255ANDC<285THENGS»"WEST":GOT0600

573 I FC>- 28 5ANDC<345THENGS -"NORTHWEST" : GOTO 6 00

575 GS-"NORTH"

600 GOSUB1000 :GOSUB5000

602 REM «<«<<< PRINT "NO ALARM" TEXT

605 PR I NT"HURRI CANE ";AS;" IS CURRENTLY ";D;" MILES ";G$;" OF"

610 PRINTI I $;". BEARING FROM "jll$

615 PR I NT" I S "; C;" DEGREES FROM TRUE NORTH."

650 GOSUB5000

700 PRI NT" I F HURRICANE ";AS;" MAINTAINS HER CURRENT SPEED OF ";SS;"

705 PR I NT"MI LES PER HOUR AND DIRECTION OF ";DD;" DEGREES FROM TRUE NORTH"

710 PRI NT"THERE IS NO CAUSE FOR ALARM. PLEASE CONTINUE TO MONITOR"

720 PR I NT"HURR I CANE ";AS;" CLOSELY."

750 GOSUB5000

800 PRINT : FORTT-ITOIOOO :NEXT : PRI NT"PRESS ENTER TO INPUT NEW STATUS ON HURRICANE "; AS ; : I NPUTUUS
810 CLS : PR I NT :GOSUB6 000 : PR I NT: G0T04 5

900 REM <<<<<<<< DETERMINE IF PATH IS IN YOUR DIRECTION

1000 KK-10: I FD<200THENKK*2 0

1001 IFD<400THENKK*15

1002 I FD<90THEN900Q
1005 PS-IIS

1050 I FDD<(CC*KK)ANDDDXCC-KK)THEN2000
1060 I FDD<KKANDCC>360-( KK-DD)THEN2000
1065 I FDD> ( 360-KK ) ANDCC<KK-( 360-DD )THEN2 000
1070 I FD<100THEN2000
1090 RETURN

84 Microcomputing, October 1979

Hurricane program is built
around some mathematical
wizardry aptly called spherical
trigonometry. Lines 98 to 470
perform the majority of the
computations. Two basic trig-
onometry equations are used
to calculate the angles and dis-
tances; the rest are conver-
sions in and out of thetrig func-
tions. The trigonometric func-
tions of the TRS-80 use radians
in their calculations, which
must be converted to and from
degrees. This accounts for
some of those long, magic-
looking numbers mixed among
the sines and cosines in the
program.

Lines 550 through 575 use
the calculated bearing from
your location to produce a ver-
bal direction (i.e., northwest,
southeast) towards the hurri-

cane. Lines 1000 through 1070
determine if the hurricane is
headed in your direction. If the
hurricane is more than 400
miles from you, the program
will take the current direction
that the storm is heading, will
compare it with the computed
direction from the storm to your
location and, if that direction is
within 10 degrees of either side
of the straight line between the
storm and you, will output the
hurricane warning. If the hurri-
cane is between 200 and 400
miles from you, 15 degrees of
variance will be used. If it is be-
tween 90 and 200 miles from
you, then 20 degrees will be
used.

Increasing the angle of vari-
ance compensates for the fact
that the closer the storm gets
to you, the less accurate the

prediction needs to be or, in
other words, the more the
chance that the storm will hit
your area.

Hurricane Conditions

Five hurricane conditions,
called HURCONS, were devel-
oped by the National Weather
Service to advise of a hurricane
threat. The HURCON number is
designed to be determined by
the amount of time it will take
the hurricane to travel from its
current location to your loca-
tion and by the movement velo-
city (minimum 50 knots) of the
storm center. The HURCON
numbers in Hurricane are strict-
ly determined by the time factor
and do not take into considera-
tion the surface wind require-
ment. Lines 2500 to 2640 calcu-
late the amount of time it will

take the hurricane to get to
your location and then select
the correct HURCON number.

One final note: HURCONS
should not be confused with
the National Weather Service
Category of Storm. HURCONS
do not advise on the intensity
of the storm, only the hurricane
threat.

The rest of the Hurricane pro-
gram lines are either used for
variable explanation (video text)
or are informational, as in the
complete listing of Hurricane
conditions.

4K Modification

If your TRS-80 does not have
16K of memory, then see Fig. 1
for the lines to delete and the
two short modifications that
will allow the program to run in
4K of memory. These modifica-
tions only take away some of
the niceties of Hurricane; the
program still retains all the
computational power of the
16K version.

You can also save memory
and personalize the program by
entering your location as string
variable 11$ in line 7 and your
latitude as variable “A” and
longitude as variable “G" in
line 8. Make sure you delete the
appropriate statements in lines
6, 7, 8 and 10 when you enter
these variables as part of the
program.

Checkout

One of the nicest things
about entering programs out of
your favorite computer maga-
zine into your microcomputer is
that you don’t have to always
understand the technical side
(i.e., equations, algorithms,
etc.) of what you are program-
ming into the microcomputer.
With many programs, if you
make a small mistake, the com-
puter (especially the TRS-80)
will let you know and, if all goes
well, it will only take a few mo-
ments to correct.

With the Hurricane program,
as with any computer program
that uses complex equations,
one or more small mistakes in
any of the mathematical func-
tions could go undetected. So,
be extra careful when you enter
those magic numbers and
equations. Just in case you

<<<<<<<< PRINT INITIAL WARNING

1095 REM
2000 CLS
2010 FORXX* 1T04
2020 PRI NTCHR$ (23)

2030 PRI NT@380, " * * HURRICANE * * "

2040 PRINT0574," * * * ALERT ***"

2 050 FORTT-1T0250 : NEXTTT :CLS : FORTT-1T010: NEXTTT
2060 NEXTXX

2400 REM <<<<<<<< COMPUTE TIME TILL IMPACT
2500 TIME-D/SS

2 52 0 TS-F I X (Tl ME ) : TB-TI ME-TS :TC-F I X(TB*60 )

2600 11*5

2605 REM <<<<<<<< DETERMINE HURCON NUMBER

2610 I FTS<72THEN I 1-4

2620 I FTS<48THENI 1*3

2630 I FTS<24THEN I I *2

2640 I FTS<12THEN I 1-1

2900 REM <<<<<<<< PRINT HURCON WARNING TEXT

3000 GOSUB6000 : PR I NT: PR I NT" * * * HURCON ";ll;" NOW IN EFFECT
3010 PR I NT"HURR I CANE ";A$;" IS CURRENTLY ";D;" MILES ";G$;" OF ";ll$

3015 PR INT"BEAR I NG FROM I I $ ; M 2 ";C;" DEGREES FROM TRUE NORTH."

3018 GOSUB5000

3020 PRI NT" I F THIS HURRICANE MAINTAINS ITS CURRENT SPEED OF "jSS;" MILES"

3030 PR I NT"PER HOUR AND CURRENT DIRECTION OF "; DD;" DEGREES, THE CENTER"

3035 PR I NT"0F THE STORM CAN BE EXPECTED TO HIT THE "; I I $

3040 PR I NT"AREA IN APPROXIMATELY ";TS;" HOURS."

3100 GOSUB5000

3200 PRINT09O2, "PRESS LETTER - H - TO INPUT NEW STATUS ON HURRICANE"

3210 PRINT" PRESS LETTER - C - TO REVIEW HURRICANE CONDITION NUMBERS";

3300 PRINT0771," * * * HURRICANE WARNING ***"

3310 FORTT-1TO200: NEXTTT

3315 PRINT0768," "

3317 FORTT-1T020 : NEXTTT

3320 MM$ » I NKEY$ : I FMM$»"H"THENCLS : PR I NT:GOSUB6000 : PR I NT :G0T045
3325 I FMM$ »"C"THENCLS : PP.I NT :GOT08000
3350 GOT03300

5000 PRINTSTRING $(63, "*") : RETURN

6000 PRINT" * * * HURRICANE LOCATION AND DISTANCE CALCULATOR * * *"

6001 RETURN

HURCON LISTING

HURRI CANE CONDI Tl ON S": PR I NT
HURCON 5: A HURRICANE READINESS STATUS"

CONSISTENT WITH SOUND PRECAUTIONARY MEASURES EFFECTIVE"

1 JUNE THROUGH 30 NOVEMBER EACH YEAR. PR I NT

B. HURCON 4: A HURRICANE HAS BECOME A THREAT"

TO THE 11$;" AREA. SURFACE WINDS IN EXCESS OF 50"

KNOTS COULD ARRIVE WITHIN 72 HOURS .": PR I NT

C. HURCON 3: A HURRICANE HAS BECOME A THREAT"

TO THE I I $ ;" AREA. SURFACE WINDS IN EXCESS OF 50"

KNOTS COULD ARRIVE WITHIN 48 HOURS."

PRESS ENTER TO CONTI NUE";UU$ :CLS

HURRICANE CONDITION S":PRINT

*" :GOSUB5000

7000 REM ««««
8000 PRINT"

8010 PRINT"

8020 PRINT"

8030 PRINT"

8040 PRINT"

8050 PRINT"

8060 PRINT"

8070 PRINT"

8080 PRINT"

8090 PRINT"

8100 PR I NT : I NPUT"
8110 PRINT:PRINT"

8120 PRINT" D. HURCON 2: A HURRICANE HAS BECOME A THREAT"

8130 PRINT" TO THE ";ll$;" AREA. SURFACE WINDS IN EXCESS OF 50"

8140 PRINT" KNOTS COULD ARRIVE WITHIN 24 HOURS .": PR I NT
8150 PRINT" E. HURCON 1: A HURRICANE HAS BECOME A THREAT"

8160 PRINT" TO THE ";ll$;" AREA. SURFACE WINDS IN EXCESS OF 50"

8170 PRINT" KNOTS COULD ARRIVE WITHIN 12 HOURS." :PRINT:PRINT

8200 INPUT" PRESS ENTER TO CONT I NUE";UU$ : CLS : GOTO 3000

8500 REM <<<<<<<< PRINT "TOO LATE" MESSAGE

9000 CLS : PRI NTCHR$( 2 3 ) : PR I NT0132 , "YOU ARE NOW IN HURRICANE "

9001 EE«FIX(LEN(A$)/2)

9002 IF EE/2<> I NTCEE/2 ) THEN EE-EE+ 1

9005 PRINT046O-EE,"*
9010 PRI NT@778,"G 0 0
9020 FORX-1T0250:NEXT
9025 PRI NT@778, "♦ - ♦
9030 F0RX»1T0250:NEXT
9050 GOT09010

* "; A$ ; " * * *"
D LUCK"

Microcomputing, October 1979 85

DELETE ALL REMARK STATEMENTS
DELETE LINES: 550 TO 575
1002

2010 TO 2060

3210

3325

8000 TO 8200
9000 TO 9050

MODIFY LINES 605 AND 3010 TO THE FOLLOWING:

605 PRINT “HURRICANE ”;A$;“ IS CURRENTLY ”;D;“ MILES
FROM”

3010 PRINT “HURRICANE ”;A$;“ IS CURRENTLY ”;D;“ MILES
FROM ”;ll$;“.”

Fig. 1. Modifications to run program in 4K of memory.

should make a mistake, I have
included some mythical hurri-
cane inputs along with the re-
sulting Hurricane projections
(see Fig. 2), which you can use
to check out your program.

Global Uses

Hurricane was designed to
be used with northerly latitudes
and westerly longitudes (i.e.,
the northern half of the western
hemisphere, which includes
the North American continent).
If you would like to go one step
further and track typhoons in
the South Pacific or snow
storms in Siberia, Hurricane
can do that for you too. There
are two basic rules you must
use for global calculations:

1. If the storm, or whatever, is
located in the southern hemi-
sphere, you must input the lati-
tude as a negative number.

2. If the storm is located in the
eastern hemisphere, you must
input the longitude as a nega-
tive number.

Any mixture of these rules may
be used. If you live in other than
the northern half of the western
hemisphere, then the same
rules apply for entering the lati-
tude and longitude of your loca-
tion.

Path Prediction

The use of straight-line pre-
dictions requires some clarifi-
cation. If you assume that the
earth is round, a straight line
between your location and the
hurricane will actually travel
through the earth. In reality, we
are finding the shortest dis-
tance between two points on
the globe and calculating the

direction, from true north,
which you would have to head
in order to take that route. The
directional calculations are
made from both locations in
order to provide the necessary
information for the Hurricane
program.

I wrote the straight-line path-
prediction portion of the Hurri-
cane program for informational
purposes in monitoring a hurri-
cane and not for use in any type
of official capacity. Hurricanes
are extremely unpredictable,
and the straight-line predic-
tions will only determine if the
storm is heading in your direc-
tion at that very moment. The
odds of the hurricane traveling
in a straight line toward your lo-
cation for any long distance are
unlikely (though possible). The
program is, however, quite ac-
curate (dependent, of course,
upon the accuracy of the infor-
mation you input) in the bear-
ings and distances it calculates.

A word of caution is neces-
sary when you demonstrate the
Hurricane program: People are
very gullible, especially when
observing information pre-
sented on a TV screen.

I demonstrated the program
during a recent computer faire
sponsored by the Panama City
Computer Society. On more
than one occasion I was ap-
proached by sincere question-
ers who asked if the mythical
hurricane I was using for an ex-
ample was real and whether
they should check with the lo-
cal weather bureau for addi-
tional information and storm
warnings. So be sure to be care-
ful in demonstrating it, espe-

cially if there is an active hurri-
cane in progress.

Acknowledgement

The spherical trigonometric
equations used in this program
came from an August 1973 QST
article written by Jerry Hall,
“Bearing and Distance Calcula-
tions by Sleight of Hand.” Jerry
had written the article for ama-
teur radio operators as an aid in
accurately pointing their beam
antennas toward other amateur
radio stations located in foreign
countries. The calculations
were done by hand from a book
with a trigonometric table in it.
There were no microcomputers
in those early pioneer years,
and the four-function, $100 cal-
culator was just coming on the
market.

Since then I’ve kept Jerry’s
article close to my heart, some-
how knowing that the micro-
computer was coming and that
I would be able to use the equa-
tions faster than either the 15
minutes it took me to do the
computations by hand or the
four minutes by calculator. It
didn’t make sense that the
foreign (DX) amateur radio sta-
tion had to wait all that time for
me to calculate whether my an-
tenna was pointed toward it or
not.

When the TRS-80 arrived in
my home in January 1978, the
time had finally come to com-
puterize the equations in Jerry’s

article. They worked beautiful-
ly, with the TRS-80 sometimes
taking as long as one second to
do the computations.

With the coming of the hurri-
cane season here in Florida, a
close friend recommended that
I modify and improve the pro-
gram so that I could use it to
monitor hurricanes. With the
aid of some locally published
disaster-preparedness infor-
mation on hurricanes, I adapted
the program for hurricane
tracking and added the predic-
tion capability.

Some Final Thoughts

The spherical trigonometric
equations used in Hurricane
could easily be adapted for in-
corporation into many other
programs. Because it calcu-
lates great-circle bearing and
distance, it should be a great
asset in navigational calcula-
tions to determine the shortest
path, along with the distance in
between . . . especially when
the TRS-80 goes portable, or
maritime mobile, whichever the
case may be. As I mentioned
above, it also lends itself to the
amateur radio operator for as-
sistance in pointing his beam
antennas.

However you use it, the Hurri-
cane program is bound to pro-
vide a global distance and di-
rection computing capability
never before available in the
home.H

INPUT:

YOUR LOCATION
Panama City
HURRICANE NAME
ANNE

LATITUDE

30.2

LATITUDE

LONGITUDE

85.8

LONGITUDE

SPEED (MPH)
45

DIRECTION OFTRAVEL(IN DEGREES)

OUTPUT:

HURRICANE LOCATION: 1285 miles south of Panama City
BEARING FROM PANAMA CITY: 193 degrees from true north
INPUT:

LATITUDE LONGITUDE DIRECTION SPEED

21 87 6 45

OUTPUT:

HURRICANE ALERT
HURCON 2 NOW IN EFFECT

HURRICANE LOCATION: 640 miles south of Panama City
BEARING FROM PANAMA CITY: 187 degrees from true north
TIME UNTIL HURRICANE REACHES PANAMA CITY: 14 hours

Fig. 2. Sample run. Hurricane program verification.

86 Microcomputing, October 1979

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Microcomputing, October 1979 87

Video DMA Interface
for SWTP Systems

Direct memory access adds speed and flexibility to the Southwest Technical Products
Corp. CT-64 video terminal. The same methods should work with many other systems.

Dewey Holten
Jerry Boehme
Department of Chemistry
Washington State University
Pullman WA 99164

T his article describes the de-
sign and implementation of
a video direct memory access
(DMA) interface for a South-
west Technical Products Cor-
poration CT-64 terminal and
6800 computer system. The
techniques and circuitry In-
volved can be easily adapted to
other computer systems and
stand-alone terminals, and is
not a final design. Basic ideas
gave us a fairly simple circuit to

experiment with in order to get
a better feel for future hard-
ware/software applications.

We will describe the video
DMA interface itself, which
gives greatly enhanced capa-
bilities for the display of alpha-
numerics and limited graphics,
with the resolution set by the
character size. In conjunction
with the mixed alphanumerics-
graphics nature of the display,
this resolution is more than
adequate for computer games,
graphs with labeled axes, bar
graphs and other applications.
Many more applications for
both alphanumerics and mod-
erate resolution graphics under
DMA control will become obvi-
ous as we proceed through the
design and construction of the

circuitry involved.

Introduction

In essence, this interface
gives a memory-mapped video
display in much the same way
the SWTP 6800 and other com-
puter systems have memory-
mapped I/O. Each character po-
sition on the screen corre-
sponds to a specific location in
memory, which can now be ac-
cessed directly by the comput-
er for loading and retrieval of
video data. For a display with
16 lines of 64 characters, which
we used for this article, this
gives IK of programmable vid-
eo output locations.

Many terminals, such as the
CT-64, also have two of these
user-selectable pages. (The cir-
cuitry will work for displays of
any length with little or no mod-
ification.) Placing a selected
character at a specific display
location can then be handled
by direct computation and pro-
cessor register-to-memory and
memory-to-memory transfer
techniques at the program exe-
cution rate.

Previously, in order to dis-
play the same character, both
the code for that character and
the complicated series of cur-
sor movements necessary to
reach the desired location
needed to be sent externally at
the much slower computer/ter-
minal transfer rate. Further-

more, the present design
change allows the computer to
use the display memory for
computation purposes when
extra memory is needed, thus
making more efficient use of
the existing hardware. Since
we use memory already sup-
plied with the terminal, this new
feature can be incorporated for
about $15 in additional compo-
nents— no additional memory
need be purchased!

The CT-64 has many useful
features: 16x32 or 16x64
character displays, scrolling or
page mode, reversed screen,
screen read (an inherent prop-
erty of the present design), indi-
vidual character highlighting
and software- and hardware-
controlled cursor movements.
Furthermore, 21L02 memory
chips are used for both the
computer and terminal display
memory, making the layout of
the new DMA system a bit easi-
er to understand. The CT-64 al-
so includes the circuitry to de-
code all 32 ASCII control char-
acters.

When a control character is
received from the computer or
keyboard a low pulse of several
pS duration is available at the
appropriate control character
pad on the main terminal board.
These can be jumpered to flip-
flops at other locations to con-
trol page flipping, cursor move-
ments, cassette read and write

CT-64

TERMINAL

Fig. 1. System architecture.

88 Microcomputing, October 1979

and numerous other user-de-
fined functions.

Limited raster scan graphics
result directly from the present
design, since a blank or re-
versed (highlighted) space can
be programmed at any of the 1 K
of character positions on a dis-
play page. For greatly in-
creased raster scan graphics
for the 6800, refer to David Koh’s
articles in the November and
December 1978 issues of Kilo-
baud (“Raster Scan Graphics
for the 6800”). Many of the DMA
techniques are shared by both
David’s and our approach. He
essentially allotted 5K of mem-
ory for a 256x160 dot resolu-
tion graphics display using an
SWTP 6800 system, CT-1024
terminal and a minimum of ad-
ditional circuitry.

We place the display of al-
phanumerics under direct MPU
control, providing the user with
greater flexibility for applica-
tions, such as rapid examina-
tion or editing of any block of
memory or monitoring the exe-
cution of a program. For those
who don’t need high-resolution
graphics capabilities or don’t
want to purchase more mem-
ory, this design will give an
easy and inexpensive means of
providing expanded display ca-
pabilities and becoming familiar
with DMA techniques.

The organization of the sys-
tem, including the video DMA
interface, is shown in Fig. 1.
The SWTP 6800 computer uses
the S-50 bus. Subsets include
the 16-line address bus, the
8-line bidirectional data bus,
read/write, system clock and
the other necessary signal and
supply voltage lines. The MPU
and memory boards share this
common set of lines, as do the
I/O ports after a certain amount
of decoding. The signals to and
from the memory boards pass
through Tri-state devices to en-
sure, for instance, that data
from only one memory board at
a time is placed on the data
bus. Since the S-50 bus uses bi-
directional data lines, the direc-
tion of data transfer to or from
the MPU (read or write) along
the common data bus lines
must be specified and requires
special bidirectional Tri-state
buffers.

In addition to the typical low-
impedance output low and low-
impedance output high states,
the Tri-state device has a high-
impedance state in which it is
essentially disconnected from
the bus. Therefore, with the en-
able control activated, the in-
put information passes directly
to the output, and with the en-
able unactivated the output as-
sumes a condition where it pre-
sents no load to the bus line.
This means we can wire-OR the
outputs of many Tri-state de-
vices on a common line, en-
abling only one device at a
time. In setting up a common
bus used by both the computer
and terminal to access the two
pages of display memory, we
used a similar type of organiza-
tion to that found m the com-
puter.

The Computer Board

The schematics of the two
boards required for the video
DMA interface are shown in
Figs. 2 and 3. The computer/
memory board, which requires
more assembly time than the
terminal board, is actually com-
posed of two sections. The first
is the entire 2K (2 page) memory
board that is presently con-
nected to the CT-64 main termi-
nal board via two 15-pin Molex
connectors, J7 and J8. The sec-
ond section is made up of the
voltage regulators and 11 inter-
face chips. The latter compo-
nents provide the usual address
and data bus interface and ad-
dress decode circuitry between
the memory and the main 50-pin
computer bus, as well as the in-
terface between the memory
and the bus shared with the ter-
minal.

We must first prepare the
CT-64 memory board for place-
ment onto the computer board.
Some readers may wish to ac-
tually rewire the 2K of memory
and page select flip-flop on the
computer board (the design for
more or less pages of display
memory remains essentially the
same).

However, we chose to use
the CT-64 memory board intact,
but with only minor modifica-
tions. The two 15-pin female
Molex edge connectors J7 and
J8 must be removed from the

CT-64 memory board. (You can
probably leave them on, how-
ever, if you have extras.) These
female connectors will be used
on the new terminal board.

The perforations on the com-
puter board accommodate the
usual 16-pin integrated circuit
sockets. This hole pattern,
however, is not compatible with
that of the five 10-pin Molex
edge connectors along the
computer bus. This turns out to
be only a minor difficulty since
you can straighten the pins on
the connectors, which are then
epoxied to the top of the com-
puter board.

Connections are made by
running the wires along the
back of the board from the ap-
propriate 1C pin to below the
edge connector and up through

a hole adjacent to the connec-
tor pin. A suitable connector
with at least 33 pins must also
be attached to the opposite
edge and will be used for the in-
terface bus to the terminal
board. We chose a 40-pin rib-
bon cable connector for this pur-
pose.

Now attach the memory
board to the computer board via
four holes in the corners of the
memory board. Small pieces of
copper wire make good feed-
through connections from the
two 15-pin rows of holes (now
called J7’ and J8’) on the mem-
ory board to the back of the
computer board.

Tables 1 and 2 indicate con-
nections for power and for Tri-
state enable lines for computer
access (C) or terminal access

Fig. 2a. Computer board schematic. Point (1) refers to a connection
of Fig. 2b. Points (C) and (T) are the computer and terminal select
lines, respectively. Note that ICs 3 and 14 are bidirectional
transceivers for the computer data lines. The entire CT-64 memory
board, with connectors removed, is mounted on the computer board.
Connection points to this board are relabeled as J7’ and J8\

Microcomputing, October 1979 89

(T) to the common memory.
Non-inverting Tri-state buffers
DM8097 (74367) are used for
much of the interfacing. Invert-
ing Tri-state transceivers
DM8835 were used for inter-
facing the display memory data
lines to the bidirectional com-
puter data bus. Two 7805 (LM-
340T) +5 V, 1 Amp voltage
regulators mounted on heat
sinks are used, one for the
CT-64 memory board section
and the other for the interface
chips. The +8 V unregulated
and ground are obtained direct-
ly from the computer bus. A 1 or
2 ^<F tantalum capacitor should
be placed between the output
and ground of each voltage reg-
ulator to provide bypassing.

The only other modifications
to the CT-64 memory board sec-
tion are to the page select flip-
flop IC31 (Fig. 2b). Cut the foils
from IC31 pins 5 and 6 to the
chip enable (CE) lines of the
lower row (page 2) and upper
row (page 1) of 21L02 memory
chips. Pins 5 and 6 of IC31 must
now be connected to pins 10
and 12 (input) of Tri-state buffer
IC4. The CE lines from page 2
and page 1 memory are then
connected to pins 9 and 1 1 (out-
puts) of IC4, respectively, as
shown in Fig. 2b.

These CE lines are also con-
nected to the outputs of the two
buffers of IC12, which are, in
turn, driven by the memory de-
code circuitry. Thus, these
memory CE lines are part of the
common bus, which can be ac-
cessed by either computer or
terminal depending on the sta-
tus of the Tri-state enable lines
of ICs 4 and 12. The data in,
data out, address and R/W lines
are similarly shared by the two
devices via Tri-state buffers ICs
1-7.

The address decode circuitry
of Fig. 2 (ICs 9-11) is wired to al-
locate the following sequential
memory locations (hex) to the
computer board:

6000-63 FF Page 1 of Display Memory
6400-67 FF Page 2 of Display Memory

This can be changed to a differ-
ent memory block by selecting
a different output pin from IC9.
(See the SWTP 4K memory
board schematic.)

The terminal has normal ac-
cess to the display memory, ex-

Fig. 2b. Computer board schematic. The connections to pin 5 and 6 of IC31 and the CE lines on the
CT-64 memory board are described in detail in the text. Voltage regulator IC33 supplies + 5 volts to
the CT-64 memory board section; whereas IC32 is for the remainder of the 1C on the computer board.

cept when the computer reads
from or writes into a location in
display memory. Under the lat-
ter conditions, the valid memory
address is decoded on the com-
puter board, forcing low either
pin 1 or 2 of NAND gate IC8, de-
pending on which page of mem-
ory the address is located. The
pin 3 output of IC8 goes high,
disabling all terminal address
and data lines through Tri-state
enable line (T).

After being inverted in a sec-
ond NAND gate, the computer
Tri-state enable line (C) goes
low, allowing the computer ac-
cess to the display memory,
i.e., during this read or write op-
eration. Note that the combina-
tion of IC8 NAND gate ensures
that only one device at a time
can access display memory.

The Terminal Board

The terminal board contains
three Tri-state buffers (ICs 5-7)
necessary for the terminal/
memory interface. These chips

are placed on the terminal
board because they also act as
drivers to maintain logic levels
through the 40-pin cable to the
computer board. The two 15-pin
Molex connectors are placed at
the J7 and J8 locations, and the
appropriate bus connector
should be attached to the top of
the board. The schematic for
the terminal board is shown in
Fig. 3. We reserved a lot of emp-
ty space on the terminal board
for increased graphics resolu-
tion circuitry; however, we de-
cided to put that circuitry on an-
other small board in the termi-
nal. (Note that, depending on
the layout, it might be better to
place ICs 5-7 on the computer
board also, if the 40-pin cable is
not excessively long. We have
used this approach successful-
ly on a second interface.)

A useful page-selection fea-
ture can also be added. An
SPDT center-off switch is
mounted on the terminal cover.
The center pole Is connected to

ground and the outer poles to
page 1 and page 2 lines (40-pin
bus #31 and #32). The center-off
position allows automatic or
control-character-generated
page select. In either of the out-
side positions the appropriate
page of memory is displayed.

Checkout

At this point the video direct
memory interface should work;
however, you may notice some
flickering occurring during the
time the display memory is be-
ing accessed by the computer.
This can be eliminated by
blanking the video output dur-
ing this time (see Fig. 4).

To test operation, simply load
the ASCII code for the charac-
ter to be displayed in the de-
sired display memory location
by using the MIKBUG memory
examine/change function. Re-
call that the ASCII equivalent
can be obtained by ANDing the
hex code with $30. For a 16 line
x 64 column display the first

90 Microcomputing, October 1979

Type

+ 5

1-4

DM8097

(74367)

5-7

DM8097

7400

74138

7402

DM8097

13,14

DM8835

15-30

21L02

10(a)

7474

14(a)

(a) Via pin 14 J8’

(b) via pin 15 J8’

row comprises locations 0-63
($00-$3F), the second, 64-127
($40-$7F), and so on. These val-
ues are to be added to the ap-
propriate address for the start
of the page ($6000 or $6400 in
the present design).

Sometimes it helps to first
clear the display page. We con-
nected the I N IT pad on the main
terminal board to CTRL A (ASCII

GND +5 Source

8 IC33

8 Terminal

7 IC33

8 IC33
3,8 IC33

7 IC33

8 IC33

9 (b) IC32

7 (b) IC32

code 01) for this purpose. Be
sure to remove C33 and D7 from
the main terminal board if INIT
is connected to a control char-
acter, as explained in the CT-64
documentation. If you have on-
ly one page of memory on the
CT-64 memory board, then
ground the page pad for the un-
used memory block.

If you encounter problems, be

(T)

(C)

1,2

1,15

3-7

1,15

3,4,5

13,14

Table 2. Tri-state enable con-
nections.

sure to check all connections
to the memory board and ad-
dress decode circuitry. If you
have two pages of memory, you
can give a memory test to one
page, while viewing the results
on the second.

Software

Undoubtedly, the video DMA
system will find the most fre-
quent use with a language such
as BASIC. You can take advan-
tage of the available computa-
tion power to control the de-
tails of the display and to add
graphics capabilities.

Listing 1 gives one such BA-
SIC demonstration program. It
requires a version containing a
memory (POKE) command,
which is used in statement 510
to load the ASCII character
codes into display memory.
You will find this program slow-
er than machine-language pro-
grams because the POKE com-
mand requires a decimal-to-
hexadecimal conversion. The
PRINT CHR$(01) commands of
line 20 are used to initialize the
terminal with a homed-up cur-
sor and clear page. The control
code 01 is decoded by the ter-
minal and is used to drive the
INIT pad located at the rear of
the main terminal board as
mentioned above.

This BASIC program simply
draws horizontal and vertical
axes, labels them and produces
a simple line curve. You can get
a feel for the interface by draw-
ing numerous other types of
curves with the mathematical
functions offered by BASIC.
You may want to use a different
routine for defining the coordi-
nate system on the 16 x 64 grid.

The CT-64 uses bit 7 from the
keyboard (an extra switch) or
from the computer to generate
individual character highlight-

Table 1. Power connections.

4 O

6 O

7 O
e O

9 O

10 <0-
3 <0

21 <Zb
16 <0-

003

-<n 14-J8

-<□ I2-J8

-< Z 2 ii- j0

-CCD'O-je

-O 9-J8
-<□ 8-J8
-<□ 7-J8

-<f~1'3-J8

-<^]lO-J7

-<]5-J7

Fig. 3. Terminal board schematic. Points (T) and (C) are the termi-
nal and computer enable lines.

ing. A highlighted space will
therefore give a white position
on the black screen or a black
position on a white screen, de-
pending on the status of the en-
tire-screen reverse function.
This highlighted (reversed)
space can be used for limited
“point” graphics with the reso-
lution being set by the cursor
(character) size.

Remember to connect the bit
7 lines in and out of the UART on
the CT-64 serial interface board.
To get a highlighted character,
simply store the appropriate
ASCII code (with bit 7 = 1) in
display memory (normal space
= $20, highlighted space =
$A0).

The CT-64 Main Terminal Board

The feature for video blank-
ing during computer access to
the display memory is quite
simple to implement. It makes
use of a previously undefined
gate on the main terminal
board. (Depending on your TV
or monitor, this feature may not
be necessary.)

Fig. 4a indicates the neces-
sary connections on the CT-64
main board. The cursor and
video dot data appear at the
output (pin 8) of exclusive OR
gate IC31C. By cutting the foil
leading from this pin you can
reroute the video data to one of
the inputs of unused AND gate
IC29B. The output of IC29B is
then connected to the inputs of
IC17A, which were previously
connected to IC31 pin 8. The

IC3I PIN 8

TERMINAL
BOARD
POINT C

Fig. 4a. Modification to the
CT-64 main terminal board for
video blanking during comput-
er access to the display mem-
ory.

Fig. 4b. Display page selection
modification.

Microcomputing, October 1979 91

0005 REM DNRAXES TEST PROGRAM
0010 Pl=24576: REM PAGE 1=16090
0020 PRINT CHR*<01>;CHR*<81>

0025. REM ftICX) IS DISPLAY NUMERAL
0038 DIM fi$(14)

0049 R$(l)="l": ft$(2) s "2" • ft$(3) =l, 3"
0045 R$<4)="4": fi$C5)= B 5": A $<6)="6 ,,

0050 f»(7)="7": Al(8)="8 n : ft$(9)= ,, 3“
0055 fl$(10)="0 H : H^dl "1” : R$(i2) x,, 2"
0066 ft$(13) =,, 3 M : R$(14)="4"

0070 REM X8 AND V9 DETERMINE ORIGIN
0075 REM ON 16 X 64 GRID
0080 REM SEE LINE 500
0085 X0=0:Y0=0
0090 X=2:A$="+"

0095 REM fi$ IS DISPLAY CHARACTER

0100 FOR Y=4 TO 14

0120 GOSUB 506

0130 NEXT Y

0140 Y=14

0158 «$="-■

0160 FOR X=2 TO 68

0179 GOSUB 509

0180 NEXT X
0190 Y=14
0200 A$= n + n

0210 FOR X=2 TO 60 STEP 4
0220 GOSUB 560
0230 NEXT X

0249 X=8

0250 FOR Y=4 TO 13
0260 fl$=ft$<14-Y)

0270 GOSUB 580
0280 NEXT V

0299 Y=15

0300 0=0

0318 FOR: X=6 TO 60 STEP 4
0320 Q=Q+i
0338 A$=ft$(Q)

0340 GOSUB 580
0350 NEXT X
0368 Y0=14:X0=2
0370 A$="*"

0330 FOR X=4 TO 60 STEP 4
0390 V=1+INT (X/7)

0480 GOSUB 580
0410 NEXT X
0429 END

0490 REM PLOT ROUTINE

0590 L=Pl+flBS(64*<Y0-Y)+AB5(X0+X)

8510 POKE( L.ASC
0528 RETURN

Listing 1. BASIC demonstration program.

other input of IC29B is then
connected via a jumper wire to
the computer (C) select line on
the terminal board (pin 33 of the
40-pin connector).

It will be necessary to first
cut the common foil grounding
pins 4 and 5 of IC29. (You may
also wish to cut the foils at pins
1 and 2 of IC29 if the page-flip-
ping feature described next will
be incorporated.) For AND gate
IC29, if either input is low, the
output will be low. When the
terminal has access to the dis-
play memory, IC29 pin 4 will be
driven low. This will force the
output of IC29 low, causing a
blank screen.

The other unused AND gate,
IC29A, can be employed in an-
other useful feature as illustrat-
ed in Fig. 4b. As mentioned
above, the page 1 and page 2
lines on the terminal board are
connected to an SPDT center-
off toggle switch (not shown in
Fig. 4). When the page switch is
in the center position and the
DPDT scroll/page switch is in
the page position, automatic
page flipping at the end of a
page occurs. Pad 16L goes low
at the end of a page to accom-
plish this.

If you wish to defeat auto-
matic page flipping, then select
the desired page with the SPDT
page switch. Automatic flip-
ping will likewise be defeated
during the scroll mode. Control-
character-generated page se-

lection is allowed in either page
or scroll modes as long as the
page select switch is in the cen-
ter-off position. A control
character other than CTRL B
can be used for this purpose.
We find all of these options
useful in management of the
two pages of display memory.

The minimum system pre-
sented above is intended to be
a low-cost and easily imple-
mented solution for the limited
display capabilities of typical
stand-alone terminals. There
are numerous opportunities for
design changes, and we have
already mentioned a few of
these. Programming for specif-
ic applications, such as moving
displays that can be externally
controlled, is the best way to
get the feel for the memory-
mapped display capabilities.
This will also provide a means
for determining future expan-
sion.

We have presented a short
program as a prototype. One
obvious use of the new capabil-
ities is rapid memory dumps
(rapid transfer of core memory
to display memory), editing and
retransfer. With increasing use
of the video DMA interface, you
will find that many display op-
erations carried out with the
slow, external computer/mem-
ory transfer can be performed
faster, more efficiently and un-
der greater control under the
present design.*

92 Microcomputing, October 1979

RADIO SHACK COMPUTER OWNERS
TRS-80 MODEL I AND MODEL II

MONTHLY

NEWSLETTER

• PRACTICAL APPLICATIONS

• BUSINESS

• GAMBLING • GAMES

• EDUCATION

• PERSONAL FINANCE

• BEGINNER’S CORNER

• NEW PRODUCTS

• SOFTWARE EXCHANGE

• MARKET PLACE

• QUESTIONS AND ANSWERS

• PROGRAM PRINTOUTS
AND MORE

PROGRAMS AND ARTICLES PUBLISHED IN OUR FIRST 12 ISSUES
INCLUDE THE FOLLOWING:

• A COMPLETE INCOME TAX PROGRAM (LONG AND SHORT FORM)

• INVENTORY CONTROL

• STOCK MARKET ANALYSIS

• WORD PROCESSING PROGRAM (FOR DISK OR CASSETTE)

• LOWER CASE MODIFICATION FOR YOUR VIDEO MONITOR OR PRINTER

• PAYROLL (FEDERAL TAX WITHHOLDING PROGRAM)

• EXTEND 16-DIGIT ACCURACY TO TRS 80 FUNCTIONS (SUCH AS
SQUARE ROOTS AND TRIGONOMETRIC FUNCTIONS)

• NEW DISK DRIVES FOR YOUR TRS-80

• PRINTER OPTIONS AVAILABLE FOR YOUR TRS-80

• A HORSE SELECTION SYSTEM*** ARITHMETIC TEACHER

• COMPLETE MAILING LIST PROGRAMS (BOTH FOR DISK OR CASSETTE
SEQUENTIAL AND RANDOM ACCESS)

• RANDOM SAMPLING***BAR GRAPH

• CHECKBOOK MAINTENANCE PROGRAM

• LEVEL II UPDATES***LEVEL II INDEX

• CREDIT CARD INFORMATION STORAGE FILE

• BEGINNER’S GUIDE TO MACHINE LANGUAGE AND ASSEMBLY
LANGUAGE

• LINE RENUMBERING

• AND CASSETTE TIPS, PROGRAM HINTS, LATEST PRODUCTS

COMING SOON (GENERAL LEDGER, ACCOUNTS PAYABLE AND
RECEIVABLE, FORTRAN 80, FINANCIAL APPLICATIONS PACKAGE,
PROGRAMS FOR HOMEOWNERS, MERGE TWO PROGRAMS,
STATISTICAL AND MATHEMATICAL PROGRAMS (BOTH
ELEMENTARY AND ADVANCED) . . . AND

WORD PROCESSING PROGRAM (Cassette or Disk)

For writing letters, text, mailing lists, etc., with each new subscriptions or renewal.

LEVEL II RAM TEST -

Checks random access memory to ensure that all memory locations are working properly.

I SEND FOR OUR 36 PAGE SOFTWARE CATALOG (INCLUDING LISTINGS OF HUNDREDS OF TRS-80 PROGRAMS AVAILABLE
I ON CASSETTE AND DISKETTE). $2.00 OR FREE WITH EACH SUBSCRIPTION OR SAMPLE ISSUE.

C. Cl 14

Box 149 New City, New York 10956

ONE YEAR SUBSCRIPTION $24

TWO YEAR SUBSCRIPTION $48

SAMPLE OF LATEST ISSUE $ 4

START MY SUBSCRIPTION WITH ISSUE

(#1 - July 1978 • #7 - January 1979 • #12 - June 1979)

NEW SUBSCRIPTION RENEWAL

iCQMRJTRQNICS

MATVgMgnCAl APRXATPNS S6P V/IC£~

HOUR

24 ORDER

LINE

( 914 ) 425-1535

CREDIT CARD NUMBER EXP. DATE _

SIGNATURE

NAME

ADDRESS

*** ADD $6/YEAR (CANADA, MEXICO) - ADD $12/YEAR AIR MAIL - OUTSIDE OF U.S.A., CANADA & MEXICO ***

v* Reader Service — see page 227

Microcomputing, October 1979

Frank J. Derfler
PO Box 17283
Montgomery AL 36117

The Ultimate Consumer Computer

Prestel, a "viewdata” system for bringing computer usage into homes and businesses in
Great Britain, was implemented by the British Post Office in January 1976. In July 1979, it
was announced that GTE has been licensed to offer an American version of Prestel.

Y ou are about to read a de-
scription of the system that
may put a cap on the growth of
consumer-style small comput-
ers in the industrialized nations
of the world. We like to talk
bravely (but perhaps with some
secret hesitation) about bring-
ing computer power into every
home. While we in the U.S. talk,
government authorities in sev-
eral European and Asian coun-
tries are doing something about
it.

Since January 1976, the Brit-
ish Post Office has been bring-
ing computer power into many
homes and offices in Great
Britain. The BPO’s Prestel
system makes unique use of
two familiar communications
devices in the home— the TV set
and the telephone— to bring ver-
satile data handling and re-
trieval service to a rapidly grow-
ing number of customers.

How Prestel Works

The accompanying block
diagram shows how Prestel is
configured. The heart of the sys-
tem is a relatively small (256K
core) computer manufactured
by General Electric Co. Ltd. of
England. This machine runs a
program that executes commu-
nications control and such func-
tions as user ID verification and
billing. Its key element is 70 to
280 megabytes of disk space.
The computer has numerous
dial-up access lines that come
in from the normal voice tele-
phone exchange system.

At the user (home) end, the
family’s TV set doubles as a
computer terminal device. Nor-
mally, the TV is bought factory
modified so that it can be used

CPU

256K CORE

How Prestel works.

as a terminal with the push of a
button. The additions (which
could be outboard) are: an auto-
dialer, which calls the computer
when the Prestel mode is select-
ed; a 75 baud transmit and 1200
baud receive modem; and a
small amount of ROM/firmware,
which contains the character
set (which could include Rus-
sian and other alphabets) and
provisions for sending six differ-
ent digits from a keypad down
the 75 baud line.

In practice, the user simply
pushes a button on the channel
selection panel. The autodialer
and ID get him on the computer
using the normal home phone
line (“Get Junior off the blower,
Mum, I want to use the telly.”).
He can then either work his way
through an extensive series of
menus or immediately select
the number of the page (just as
in a newspaper) of information
he wants.

The TV display he sees has
about the same graphics and
color impact as the Apple II. The
big difference is that he has
many megabytes of constantly

updated information to back
him up.

As we well know, a computer
system is nothing without soft-
ware. Generally, microcomputer
systems have it all over Prestel
in the area of specialized
number crunching. If you do a
lot of curve fitting and stress
analysis, then a dedicated sys-
tem would serve you better.
Also, if you need your own
unique data base, a dedicated
system is a must.

Prestel Services

Prestel puts you into the
public data base in an inter-
active mode. This public data
base includes everything you
see in the daily papers. It also in-
cludes near real-time stock and
racetrack reports. Airplane and
train schedules, encyclopedias,
recipes, specialized corporate
news (either for public or re-
stricted access) and a host of
other kinds of information is
available. Services (interactive
computer programs) such as
loan balance, investments,
checkbook and, yes, even

games will be added to the sys-
tem by early 1981.

The BPO is entering a market
trial phase during which they
will greatly increase the number
of customers. They will estab-
lish ten computer centers during
1979. Each center will serve
customers in a local calling
area. Over 300 companies have
contracted to be information
providers. These include major
newspapers (the New York
Times), retailers, investment
and financial firms and even
“umbrella” organizations that
buy blocks of space (a minimum
of 100 pages from the BPO costs
about $2500 per year) and resell
it to smaller users.

Late in the year, users will be
able to send specific orders
(adding a credit card number) or
requests for further information
to the retailers by using their
keypad. Even betting is possi-
ble, but collecting is between
you and the bookie or retailer;
the BPO only supplies the com-
munications channel.

Another feature coming in the
near future is the capability of
sending pre-formatted mes-
sages from one subscriber to
another. Messages such as “I

will arrive at ” or “Call me

at . . . can be selected, filled in
and placed in a file for another
terminal. This system is similar
to mailboxes on other time-
shared systems, except that the
originators have only limited
numeric pads for input. If re-
quired, standard keyboards are
available for users.

Application

The key to the acceptance of
consumer-oriented computing

94 Microcomputing, October 1979

is cost. The cost must be low
enough so that the system
leaves the category of “adult
toy” and becomes an accepted
major appliance. Prestel
achieves this by using in-place
phone lines and television
displays in a dual-purpose role
and by billing the user by the
amount of use.

The added electronics need-
ed to make a TV set into a
Prestel terminal presently
doubles the price of the set. This
cost is expected to drop rapidly
as larger production runs are
made. An add-on converter is
being produced, but the eco-
nomics of TV in Great Britain is
such that the majority of re-
ceivers are leased. In practice,
the old receiver is swapped for a
new modified one, and the
amount of the monthly lease is
increased.

The Prestel service is paid for
on a page-by-page basis. Each
page of information (not in-
dexes) has a use charge, which
is levied by the company or ser-
vice that provides the informa-
tion. The charge, which varies
between one-half and 30 U.S.
cents per page, is shown on the
index so the user knows the
price of a selection before he
makes it.

Many pages are, of course,
free. These may contain com-
mercial messages, surveys or
complementary services (com-
pute payments or future value of
deposits, etc.). An important
part of the central computer’s
software is involved in keeping
track of any appropriate charge
for each page selected. A cur-
rent bill is always available for
the customer’s viewing (that’s a
free page too).

Other Countries

The generic name for the kind
of service Prestel provides is
viewdata. Before I lead you to
believe that the BPO, or even the
British in general, are alone in
bringing this technology into
people’s homes, I should men-
tion the other forms of viewdata
that are maturing almost as
fast.

There exist competing British
systems that use the flyback
time on regular television broad-
cast signals to transmit the

video information. The Japa-
nese are well along the way with
a system called Captain, which
will be available to about 1000
subscribers in the Tokyo area
sometime in 1979. The German
Bildshirmtext is being based on
software purchased from the
BPO. Captain has about 100,000

pages of text available. One of
Japan’s goals includes produc-
tion of a $500 adapter unit.
Some of the biggest names in
the Japanese electronics in-
dustry are involved in this proj-
ect, and there is no reason to
believe they will not reach their
goal quickly.

The French are also develop-
ing a viewdata system. Almost
predictably, they are lobbying
for a set of standards and for-
mats different from what most
of the other countries are using.
Prestel software has already
been sold to West Germany and
the Netherlands. Switzerland,
Finland, Sweden and others are
negotiating seriously. When I

talked with John Darkin, the
manager of international mar-
keting operations for Prestel, he
also mentioned that several of
his sales representatives had
plane tickets to Moscow in their
pockets.

As you read the preceding
paragraphs, you may have

looked for some mention of the
major Western industrialized
nation with the largest (and
best) telephone system, the
greatest number of television
sets and the largest appetite
(mania?) for information in the
world. You looked In vain. The
countries involved in the view-
data evolution have one thing in
common: a government monop-
oly telecommunications system
that doesn’t discriminate be-
tween transmission media and
special services on that media.

In order to build the world’s
best telephone system, the U.S.
had to develop a similar “pro-
tected market” situation. More
recently, we seem to have be-

come ashamed of big business,
and we have tried to regulate
equality. That these new regula-
tions have been beneficial In
some areas is beyond question,
but they have also stood in the
way of the large-scale corporate
cooperation needed to bring
viewdata service to the U.S.

mass market. The regulatory ins
and outs are beyond the scope
of this article, but straight-line
extrapolation says that it will be
a long time before regulatory re-
strictions ease. (Breakthroughs
are possible.) Some cable tele-
vision companies have con-
sidered small-scale viewdata
operations, but their data base
would probably be tiny in com-
parison.

The Digicast project, which
exists in the minds of some
serious computer folks in the
environs of Stanford University,
is probably the closest thing to
the viewdata concept in the U.S.
This system would be broadcast
on the sub-carrier of standard

meteorological Offica

Page 109a

list of information on prestel

Heus & Weather Sport £ - c-> >.
Eniertai nine n t Ho i * cjeys &
Marketplace Jobs & Career

Adv t ce Books A Re * >

House & Garden

BUSINESS PRESTEL
SPECIAL DATABASES

PRESTEL GUIDE

8 PRESENTING PRESTEL

9 TO LEAVE

For alphabetical index

Prestel

meteorological

Office

National weather forecast
Regional A special forecasts,
uh i ch i nc I ude

Hobbies, sports A special events
Ho I i day A t rave I
Sh i pp i ng A sa « I i ng
Agriculture A horticulture
Flying A gliding

Reports of actual weather conditions
Statistics Averages

Past weather detaJs
How can the Met. Office help VOU 17

Page 262a

Higher education B
further education

Local colleges of further education
Un i vers i t ies

Adu l t schoo I s
Evening classes
Cor respondence courses
Trade, vocational A professional
training

La nguage schoo I s

: O EXPERIMENT

Page 2631a

Education

0 An Experiment in Programmed
i_ea r n 1 ng

1 Junior School Topics

2 Mu I t i p I e Cho 1 ce Ques t ions

3 CAI (Under task control )

4 Exam > nat ion Revision Notes

5 Graded Quizzes

6 -revious Examination Papers

7 Computer Aided Instruction

8 The Laboratory On The Screen
S Decision Making in Medicine

'ey number for requi red section

The Prestel menu can lead the user through the thousands of available pages. The unique educational
and weather services shown here are possible because of the large disk space open to each home
terminal.

Microcomputing, October 1979 95

for the TRS-80 from Micro- Mega

commercial FM stations. But for
now, they are planning to op-

by hardware may be able to have
our cake and eat it too, but

CASSETTE CONTROL UNIT

• Speed up your cassette tape handling • Pinpoint program locations on tape with an audible monitor •
Get protection from recording and playback glitches resulting from ground loops • Eliminate the tedious
plugging and unplugging of recorder cables

The Micro-Mega Cassette Control Unit does all this and more. You get ins t
manual control of the recorder at the flick of a switch. Want to find the
beginning or end of a program? Flick another switch and you'll hear it. All
cables remain plugged in all the time

The Micro-Mega Cassette Control Unit does a lot to improve the appear-
ance of your TRS-80 system, too. As shown, it's in a 2'/i ’’ x 5" box which
snuggles between the keyboard and your recorder. There is no need to
move the recorder, and all cables come neatly into the unit. The Cassette
Control Unit is tailored to the CTR-41 recorder, but may be used with most
other recorders as well.

CASSETTE CONTROL UNIT. $37.50

Add $1.00 for postage and handling

CPU MONITOR

Ever find yourself with a blank screen wondering what your computer is up to? The Micro-Mega CPU Monitor
can tell you, for example: • If your CPU is in a loop with no exit, • When a long sort is nearing completion,
or • If a key bounces during keyboard input. The CPU Monitor lets you listen to all CSAVEs and CLOADs
and will help you quickly find the correct recorder volume setting. If you have an expansion interface, you
will always know whether the real time clock is on or off because you can hear it.

The Micro-Mega CPU Monitor gives a voice to the Z-80 microprocessor In
your TRS-80 by using AM radio circuitry to pick up the computational
rhythms of the CPU. which are amplified and played through a loudspeaker.

The pickup unit of the CPU Monitor, shown at left in the photo, goes under
your TRS-80 keyboard. It is connected by a 36" cable to the speaker and
control unit, which includes an onJotf volume control and an LED "power-
on" indicator. The Monitor is powered by an AC adapter, shown at right in
the photo. No batteries are needed and no electrical connections to your
TRS-80 are required.

By listening to the CPU Monitor, you will soon become familiar with the "personalities " of the programs you
run and whether they are executing in a normal way. A dramatic use of the CPU Monitor is in the great
enhancement which it provides for computer games. (See "Gaming Environment" below.)

CPU MONITOR $ 47.50

Add $ 2.00 for postage and handling

THE GREEN-SCREEN

The eye-pleasing Green-Screen fits over the CRT of your TRS-80 Video Display and gives you improved con-
trast with reduced glare. You get bright, luminous green characters and graphics like those featured by very
expensive CRT units.

The Green-Screen is closely matched to the color and texture of the TRS-80
Video Display and improves the overall appearance of your system. It is at-
tached with adhesive strips, which do not mar your display unit in any way.

The Micro-Mega Green-Screen gives improved video display visibility for all
applications and is especially effective in creating dramatic, high-impact
displays for computer games. (See "Gaming Environment" below.)

THE GREEN-SCREEN $1150

Add $1.00 for postage and handling

THE ULTIMATE STAR TREK PACKAGE

Tired of trivial computer games? This complete Star Trek package will provide you with endless fascination
and challenge. In addition to the program cassette, it includes comprehensive instructions, a pad of
"Voyage Log" record sheets, and a free standing "Torpedo and Maneuvering Chart."

The package is built around the latest version of Lance Mlcklus' incom-
parable Star Trek III, a 13,000 byte program with a host of subtle and imag- :
inative features, which include numerous dynamic and spectacular graphic
displays. Star Trek III puts you In command of the Enterprise cruising in a
galaxy of 192 quadrants filled with uncharted hazards, Including hostile
Klingons, pulsars, and black holes. You have at your disposal scanners,
various weapons and defense systems, on-board computers, and a loyal
crew. (You will need them all to survive the Klingons.)

Your mission is to rid the region of Klingons and to locate five inhabitable planets, all within 300 stardays,
before returning to Star Fleet Headquarters where your overall effectiveness as a starship commander will
be scored. High scores are possible only with careful planning and effective battle tactics. The "Voyage
Log" sheets will guide your strategy , and the "Torpedo and Maneuvering Chart" will give you a vital edge in
combat. ( When you engage three Klingon ships you can't afford to miss.)

STAR TREK PACKAGE (for Level II, 16K only). $ 22.50

Add $1.00 for postage and handling

CREATE YOUR OWN SPECTACULAR
GAMING ENVIRONMENT (and save 15.00)

The Enterprise is in battle trim with deflector shields at full power. As her captain, you are taking her into
combat. The battle-stations siren rings in your ears and "CONDITION RED" flashes on your monitor screen.
You call for warp drive and key in the coordinates of the quadrant where your scanners have detected Kling-
on ships. As you select the warp factor, you hear the reassuring clicking of your navigational gear as it ac-
tivates the warp drive.

Suddenly, you break out of hyperspace and your monitor displays the chilling sight of three Klingon Battle
Cruisers floating on your screen! Their evil shapes glow in luminous green against the black void of space.
Moments later, you hear the characteristic rasping sound of Klingon laser weapons, and, as you watch,
high-energy beams come knifing toward the Enterprise in succession from each of the Klingon ships.

You have been hit! You hear the dismal sound of the damage control alarm as "DAMAGE TO WARP DRIVE”
and "DAMAGE TO PHASERS" flash on your screen. The Klingons have stopped firing! The Enterprise is
crippled, but your best weapon is still intact, and It's your turn now! You key in the command for photon
torpedoes. As your screen again displays the position of the Klingon ships, you select a firing vector from
your torpedo chart and key it in. Now you hear the buzz of your photon torpedo as you see it speeding toward
a Klingon ship. It strikes him dead-center ! As you watch, the Klingon Battle Cruiser disintegrates, accompa-
nied by a satisfying crackling sound.

Does the above scenario sound far fetched? Not at all. It s a small sample of what you will experience with
Micro-Mega's Gaming Environment, which consists of: • The STAR TREK PACKAGE • The GREEN-
SCREEN and • The CPU MONITOR. The fast-paced and dynamic action ref lects the superb Star Trek III pro-
gram together with the "Voyage Log" and "Torpedo Chart" of the Star Trek Package. All of the unique
graphic displays are greatly enhanced by the Green-Screen. Finally, the uncanny sound effects are pro-
duced by the CPU Monitor, which faithfully picks up the FOR, NEXT loops and other CPU patterns, which
create the distinctive siren sounds that accompany the ALERT and DAMAGE messages along with the
harsher notes of the weapons salvos. Once you've tried it. you won’t any longer be satisfied with silent com
puter games.

Remember that with the Gaming Environment you also get all of the other excellent features of the CPU
Monitor and the Green-Screen tor non-gaming applications. You also save $ 5.00 off the combined cost of
the individual items.

GAMING ENVIRONMENT. $76.50

Add $3.50 for postage and handling

Terms: Check or money order, no CODs or credit cards, please. Add amount
shown for postage and handling to price of the item. All items shipped within 48
hours by first class or priority mail. Virginia residents, add 4% sales tax.

M54

Micro -Mega • P.O. Box 6265 • Arlington, Va 22206

erate in a distributed processing
mode. The raw data base would
be broadcast, and each custom-
er would use a “smart” receiver
(FM tuner feeding a microcom-
puter) to sort and present the
data according to instructions
contained in local program-
ming. This is an interesting con-
cept in that it puts the data base
in the sky and allows the user to
pick out what he wants, but it
doesn’t seem to have the eco-
nomic incentives (and therefore
growth potentials) built into it
that viewdata/Prestel does.

Digicast is a different ap-
proach that may be valuable at
some future time when users
can add to or modify the data
base, but for now it lacks com-
mercial attractiveness. The cen-
tralization of the viewdata sys-
tems may not appeal to home
computer hardware buffs, but it
has great software advantages.

Certainly, the software asso-
ciated with a viewdata system
is not difficult to write. The hard-
ware is well within present pro-
duction capabilities, but some-
one with a lot of money and
horsepower will have to or-
chestrate the regulatory and
commercial problems before
the system comes to the U.S.

The Future of the Microcom-
puter Industry

My prediction is that where
viewdata comes, personal com-
puting through the use of micro-
computers will not flourish. But,
at the same time, the use of
computers in small businesses
will grow strongly. My reasoning
relies on the observation that
most home computer users real-
ly don’t need or develop their
own data base. They may have a
lot of programs, but they prob-
ably don’t have anything in the
way of unique data that cannot
be stored as easily on 3 x 5
cards. Access to these same
programs, plus the availability
of a huge public data base,
would clearly provide more
value than a microcomputer
system in the same general
price range. Certainly all
viewdata terminals don’t have to
be “dumb.”

Those of us interested in hob-

small-computer makers and
sellers will generally find them-
selves crowded out of the home
market by the big appliance
manufacturers. The small-
business market will benefit,
however, from the psycho/socio-
logical impact of having com-
puting power available in the
home. As people become more
accustomed to interacting with
data display devices, they will
lose their fear of the technology
and look for more services out-
side the home.

Right now we tend to think of
small-business computers as
aids for bookkeepers. Public fa-
miliarity with the viewdata type
of display may eventually allow
use of small-computer systems
as aids for sales clerks too.
Product information can be
made available on many ter-
minals around the store. Cus-
tomers can use their viewdata
skills to gather detailed informa-
tion about the products or ser-
vices offered. The local store
computer (a micro will handle
several terminals) can lead a
hardware store customer
through the process of selecting
just the right nut and bolt for the
job. The local data base can
then tell him which aisle it is in
and how much it costs.

The smart businessman or
programmer in the small-com-
puter field right now can an-
ticipate change and get out
ahead of it. Remember, a leader
is just someone who is out
ahead of the pack running in the
same direction. The lesson of
Prestel is that big homogenous
populations (home users) can
effectively utilize a large cen-
tralized data base. Microcom-
puter systems are best for small
users with a unique data base.
Run in that direction.

For a while, we in the U.S. may
continue to play with embryonic
networking schemes and to mail
each other “magazines” on
cassette tape, but we should
know that there is a great wave
building off either shore. We can
either grab a board and ride the
curl or be wiped out before we
even see it. Keep your eyes on
the horizon because viewdata
may be here soon. ■

96 Microcomputing, October 1979

We're about to make
a new name for ourselves.

Not that the old one was so bad. As
Ithaca Audio, we've made quite a name for
ourselves. As the source for CPU, memory,
video display and disk controller boards to
upgrade other makers' mainframes and
peripherals. The company that makes
those neat little RAM expansion kits. And
the folks behind the world's only Z-80
Pascal compiler.

But as much as we've enjoyed im-
proving other people's equipment, we've
been quietly moving towards larger en-
deavors, with a lot of encouragement from
our customers. Listening to people's prob-
lems, as well as their needs. And, as a prime
mover behind the IEEE S-100 Bus Standard,
answering some really knotty questions.

One of the results is our new identity.
And our first new product: the Inter-
systems DPS-1. An IEEE S-100 compatible
mainframe with features that live up to its
looks. Dependable operation to 4 MHz.
Twenty-card capacity. A modular power

supply. And something no one else has—
built-in breakpoints to give you a faster,
more powerful tool for testing software as
well as hardware. Directly accessible from
an easy-to-use front panel that's as reliable
as it is functional. In short, an intelligently-
designed computer for the intelligent user.

There's a lot more to Intersystems. In
hardware. And software. All available
through the nationwide dealer network
we're now assembling.

You can watch this magazine for
updates. Or contact us directly for straight,
friendly answers and detailed information
from key staff people. Just the way you
always have. Because even though we're
making a new name for ourselves, we'll
never forget who made it possible.

]oDfeo% v MeooD^

Ithaca Intersystems Inc.

1650 Hanshaw Road/R O. Box 91
Ithaca, NY 14850/607-257-0190

Bill Harvey
204 Vienna Drive
Milpitas CA 95035

The Exatron Stringy Floppy

The ESF is a device for those who don’t want a cassette system and can’t afford a disk.

A t some point, your system
will outgrow its memory to
store all those “neat” pro-
grams. In the meantime, you
have to suffer through waiting
for your cassette (or, heaven
forbid, your Teletype!) to load
and store your creations. At
present you have a Super
13.978K Ultra-Extended BASIC
(FORTRAN, COBOL, Trek game,
etc.) that loads in under two (or
maybe 20) minutes ... if you
have set the tape counter cor-
rectly and remembered to
switch off the pause control . . .
if the volume and tone controls
have not shifted since last time
you used them . . . and If your

little brother has not used the
tape to record secret messages!
That is, after you rewind the cas-
sette (45 seconds), because the
program you want is always on
the other side. It may be time to
look for something a little bit
faster.

Have you got $700 to $1100,
16 hours for assembly time and
the patience of Job to interface
that “great” software-all to
invest in a mini-floppy? No?
Well, have I got just the thing
for you.

How does 7.2K bits/sec trans-
fer rate sound . . . full software
control of transport in EPROM
(2708) . . . 45,000 bytes of stor-

age per wafer . . . three extra
EPROM sockets for your own
use . . . completely assembled,
tested and ready to run (plug it
in, turn it on and GO!) . . . and it
really works ... all for less than
$300? Sound like a possible
winner? Read on, friend.

The ESF Package

The item under discussion is
the Exatron Stringy Floppy. Ex-
atron is the maker of a line of in-
dustrial automated 1C testers
and three computer products:
the Exatron Stringy Floppy
(ESF), an unusual 36K RAM/
EROM Memory Card and a soon-
to-be-released EPROM Pro-

grammer, all S-100 bus oriented.
In plain English, the ESF is a
completely assembled and
tested endless-loop-tape mass-
storage system complete with
transport, controller/EPROM
software printed circuit board
(presently available as an S-100
bus card suitable for 8080 or
Z-80 operation. Exatron is now
advertising one for the SWTP
6800), 6K assembler-editor
monitor and several blank tape
wafers.

With the ESF is included a
complete head cleaning kit to
ensure long lead life. The
owner’s manual, sold separately
so that potential purchasers can
determine the suitability of the
ESF Mass Storage Subsystem
for their proposed use, contains
one of the most complete de-
scriptions of a computer prod-
uct I have ever seen. The man-
ual contains a description of
the product, installation and
checkout, operation (general),
utility program descriptions
with flowcharts (24 pages of
flowcharts alone!) and a com-
plete source-code listing of the
software, troubleshooting pro-
cedures for transport and con-
troller, plus manufacturer data
sheets for the LSI chips used in
the ESF— an excellent value in
itself.

Both the manual and ESF are
supplied with a 30-day money-

Complete Stringy Floppy system as received with transport, controller, PC board and test wafer. The
white 1C is the 2708 software EPROM with room for three more 2708s on board. Addressing must be in
the same 4K block, typically B000 or D000.

98 Microcomputing, October 1979

My home-brew system with (left to right) cassette recorder , con-
sole/CRT, Exatron Stringy Floppy and paper-tape reader. The
mainframe is mounted in the homemade desk behind the door in
the lower right.

back guarantee. The ESF comes
with a one-year normal-service
warranty. And with a $10 sec-
ond-year membership in the Ex-
atron Stringy Floppy Owner’s
Association (ESFOA)— -the first
year’s membership is included
with the owner’s manual— you
get a second year’s warranty
for the ESF. Unheard of, you
say? Too good to be true? My
initial thoughts exactly.

My first introduction to
Stringy Floppy was at a local
computer repair/design shop
where a Stringy Floppy was be-
ing custom-fitted into a demo
computer. Not having the afore-
mentioned $700 to $1100, and
as I was looking for an alterna-
tive to my cassette system, I in-
vestigated further.

I went to Exatron to purchase
an owner’s manual and to check
out the company behind this
unusual product. I was wel-
comed in by Bob and Mike
Howell, the owners/operators of
Exatron. After a long discus-
sion and a short tour, I was on
my way home to study my
owner’s manual in preparation
for the Saturday-morning users
group meeting, of which I was
now a member. I figured this
was a chance to seek out dis-
gruntled owners and find the
product’s weaknesses! No such
luck, though.

Everyone there had had good
luck getting the ESF running
quickly with almost no prob-
lems, save one experienced by

a user with a Z-80 System. He
later discovered a defective dy-
namic memory card that, when
removed, improved his success
rate significantly.

The ESFOA also issues a pro-
fessionally produced monthly
newsletter that is distributed to
all members. Topics include in-
terfacing techniques for popu-
lar BASICS, save-load routine
descriptions for the assembler,
utility-software routine sum-
maries and topics of discus-
sion at the ESFOA Saturday
meetings.

With the product seemingly
standing head and shoulders
above the competition in rela-
tion to value for money, I
plunked my money down. In on-
ly four days I had my Stringy
Floppy, and off I went to ponder,
“Why doesn’t it work?” You
see, I have a Turn-key, home-
built, S-100 bus system, cur-
rently running a TDL Z-80 CPU
with 25K of static RAM, IK of
PROM, 32-character-per-line
CRT with keyboard, cassette in-
terface and paper-tape reader.
Nothing, especially software,
seems to be readily compatible
with my system. So a hardware/
software combination could
never work without modifica-
tion.

Surprise! It worked the first
time! The only modification re-
quired was a change in soft-
ware to move the error display
from the front panel to my CRT.
Even this is in RAM, so no

Close-up of peripherals.

EPROM change was required.

Installation and Testing

Let me describe a typical in-
stallation and checkout of an
ESF. The box that the ESF ar-
rives in has a cut-to-fit foam
liner that offers excellent pro-
tection during transport. The
package contains the Stringy
Floppy Transport, hard-wired to
the controller printed circuit

board and a head-cleaning kit.
Several wafers, one with the as-
sembler/editor to start you off,
are also included.

Following the instructions in
the owner’s manual, insert the
controller into an empty slot in
your S-100 bus. The three-foot
interconnect cable allows con-
venient placement of the tape
transport. Check to see that
you have no memory or other

Stringy Floppy tape transport with wafer ready for insertion.

0000

BEG LXI SP, 0400 H

0003

LX1 H, SHOW

0006

PUSH H

0007

LXI H, 4250D

000 A

PUSH H

000 B

JMP0DD02H

00OE

SHOW CMA

000 F

OUT OFFH

0011

JMP BEG

To certify we set the stack, push the Return if Error address, push the byte count re-
quired to nearly fill a 5 foot wafer, jump to the Certify routine in EPROM, display
results on the programmed output port, and return to start to run the test, again.

Table 1.

Microcomputing, October 1979 99

Controller card for Stringy Floppy.

device addressed to the D000H
block as the controller is as-
signed to this block and may
conflict with other devices if
similarly addressed.

After turning your computer
on, you must enter a short “Cer-
tify” program, as shown in
Table 1. This will allow certifi-
cation of your wafers, a pro-
cess that is necessary with all
new wafers. Because the wafers
are the endless-loop type, sev-
eral complete passes may be
necessary to distribute the
tape lubricant before accurate
results can be obtained.

Certifying runs the tape in
and checks the reliability at the
same time. Any errors detected

will normally be displayed on
the front panel according to the
chart in Table 2. (In my system
the error is taken from the “A”
register and output to a port to
be displayed on the CRT. No
display = no errors.)

Successfully certifying a wa-
fer means you have simulta-
neously tested the transport
and controller printed circuit
board. Writing a wafer with
data is the next test.

The software contains three
“Quick Store” routines de-
signed to write 1, 4 and 8K
blocks that start storing data
from 0000H upward. The proce-
dure is to select a wafer of the
appropriate length, five feet for

1 or4K, ten feet or longer for 8K,
insert it into the transport and
execute the address shown in
Table 3.

The transport will start up
and start looking for the end-of-
tape/beginning-of-tape marker.
Upon detection, it will check to
see if the write-protect decal is
in place. If it is not there, the
procedure is aborted with an
appropriate error code dis-
played. Otherwise, the Write
LED will come on indicating the
storage of data. Upon comple-
tion, control will return to
0000H.

Similar “Quick Load” pro-
grams are available to comple-
ment the “Quick Store” rou-
tines. It is only necessary to in-
sert a wafer with a “Quick
Stored” program in the trans-
port and execute the appropri-
ate address in Table 4 accord-
ing to the recorded block
length.

With a successful! write/rec-
ord test the unit has completed
its checkout. It is now ready for
use.

Software

The software contains many
other routines too numerous to
explain in detail at this time,
but they are listed in Table 5. In
general, the ESF software al-
lows the reading and writing of
data in a length to 40K with
user defined “User’s Return
with Error Address,” “Control
Transfer Address” (possible
Auto-Start or Load’N Go), Block
Length with Begin and End Ad-
dresses and File Number rou-
tines to aid in location of a par-
ticular file among many on a
wafer.

There are also routines to
“Verify” a wafer against mem-
ory, “Add” a file to a wafer,
“Write and Verify,” “Add and

Verify” and “Park,” that is,
move the tape in the wafer to a
point where the end-of-tape de-
cal is placed in the opening to
protect the magnetic portion
from accidental harm.

But how does the Stringy
Floppy really perform? Just
fine thanks! That is not to say it
is perfect, just that it operated
the first time, is still working
and gives me a certain feeling
of confidence about further op-
eration. It is certainly not of the
type of quality normally expect-
ed of the hobbyist market. It is
of the best “commercial” quali-
ty in terms of material, assem-
bly and software.

The minor problems include
not being able to consistently
get 50-foot tapes to run on my
unit and documentation that,
although may be a cut above
the competition, is still some-
what incomplete. This latter
problem is being corrected by
the ESF Newsletter. Exatron
has been most helpful in at-
tempting to solve my tape prob-
lem, and I am sure we will re-
solve it soon. Other users have
not made mention of any tape
problems, so this may be a one
of a kind.

Conclusion

For those who need an alter-
native to a relatively slow, man-
ually operated cassette system
and who cannot afford the time
and money for a floppy disk the
Stringy Floppy is the only way
to go. The price is right, the
quality is high, and the system
works with little or no effort,
which, I think, is the key. Hard
to believe from a hobbyist com-
puter company, but true. Very
true.B

EXATRON
3555 Ryder Street
Santa Clara CA 95051

Error Code

Programmed

ASCII

Complement

Output

Character

In A-Register

NO MORE TAPE

21 Hex

DE Hex

WRITE-PROTECTED

23 Hex

DC Hex

NO FILE NUMBER

25 Hex

DA Hex

MANY PARITY ERRORS

26 Hex

D9 Hex

Table 2.

LABEL

ADDRESS

FROM

FILE#

STOR1

DF2D

0000 H

3F0H

FFF1

STOR4

DF39

0000H

0FF0H

FFF4

STOR8

DF45

0000H

1FF0H

FFF8

Table 3. Quick Store routines.

LABEL

ADDRESS

FROM

EXECUTE STARTS

LOAD1

DF07

0000

03F0H

0000 H

LOAD4

DF10

0000

0FF0H

0000 H

LOAD8

DF19

0000

1FF0H

0000 H

Table 4. Quick Load routines.

CERTIFY

Certify a wafer

WRITE

Write a file

READ

Read a file

VERIFY

Verify a file against memory

ADD

Add a file to a wafer in addition to the current file already recorded

WRITE &

VERIFY
ADD &

Write a file and verify

VERIFY

Add a file to the wafer and verify

PARK

Park the wafer in a protected position

Table 5. General-purpose utility procedures.

100 Microcomputing, October 1979

Exatron

Stringy Floppy Update

Since the article by Bill
Harvey was written, Exatron has
developed a TRS-80 version of
the Stringy Floppy, with PET and
Apple versions soon to be re-
leased. The main difference be-
tween the S-100 version and the
newer TRS-80 version is in ease
of operation— the TRS-80 model
just plugs into the keyboard and
wall socket. Both data and pro-
grams can be stored on the unit,
up to ten programs or sets of
data per wafer.

The cost of the TRS-80 ver-
sion is $249.50 plus shipping.
We now have one of the units in
our microlab and will publish a
complete user report in the near
future. From our experience
with the stringy floppy so far, it
looks like the ideal compromise
between cassette and disk for
the microcomputer user— it’s in-
expensive and fast.

Jim Perry
Microcomputing
Projects Editor

" Actually , it’s a tridirectional printer. It prints left/right, right/left
and wherever it wants”

We’re looking for names and addresses of TRS-80
newsletters . If you produce or are affiliated with
such a newsletter, please drop a line to:

Bob LaPointe, Circulation Manager
MICROCOMPUTING
Peterborough NH 03458

Thanks.

use TRcopy

WITH YOUR LEVEL II TRS-80*

TRcopy is a cassette tape copying system that lets
you SEE what your computer is reading.

COPY ANY CASSETTE TAPE * 0

With the TRcopy system you can copy any TRS-
80 Level n cassette tape whether it is coded in
Basic or in machine language. You can also copy
data created by programs and you can copy assem-
bler listings.

YOU CAN SEE THE DATA

As the tape is being loaded, you can SEE the
actual data byte-for-byte from the beginning to the
end of the program. Up to 320 bytes are displayed
at one time. ASCII characters are displayed on the
first line and hexadecimal code is displayed on the
following two lines. Data is displayed exactly as it
is input including memory locations and check sums.

IDENTIFY PROGRAMS

With TRcopy you can identify programs on cas-
sette tapes without written documentation because
you can SEE the filename. If you forget to label a
tape, you can use TRcopy to display the tape contents
and identify the cassette.

VERIFY CASSETTE TAPES

With TRcopy you can verify both the original tape
and the tape copies. You can make certain that your
machine reads the original tape correctly and that it
makes byte-for-byte copies. TRcopy also counts as
it reads giving you the exact length of the data.

MAKE BACKUPS FOR YOUR PROGRAMS

Now you can make backup copies of your valuable
programs. Many times a cassette that you make will
load better than one that is mass produced. The
original can then be kept as a backup in case the
copy is damaged.

MAKE COPIES OF YOUR SOFTWARE

If you are in the software business you can use
TRcopy to make tested copies of your programs for
sales distribution. TRcopy produces machine lan-
guage tapes that are more efficient than those pro-
duced by the assembler itself.

RECOVER FAULTY DATA

With TRcopy you can experiment with the volume
and level controls and you can SEE what the computer
is reading — even if your computer will not read the
data through normal read instructions! In this way it
is possible to read and copy faulty tapes by adjusting
the volume control until you SEE that the data is
input properly.

SIMPLE - FASCINATING - FUN

TRcopy is not only a practical utility program.lt
is also a fascinating graphics program that lets you
SEE, for the first time, cassette data as your com-
puter is reading it. And it’s as simple as 1-2-3.
Just load, verify and copy. You will now be able to
use cassette tapes with confidence knowing that
TRcopy is there when you need it.

The TRcopy system is a machine language program
with documentation explaining tape leaders, sync
bytes, check sums and other formatting conventions.
With the TRcopy system, you can SEE what you are
doing!

TRcopy System Including

Cassette Tape and Documentation

Orders accompanied by money order r mv

or cashier's check mailed same day.

Orders paid by other check shipped in 14 days. No COD's. Return
within 10 doys for a full refund if you are not satisfied.

YOUR

ORDER

.ill!

si!!;

s Hi! i
|5lli l
Ejiff \
l fiitl i

O 1 ° .5 8. >

‘ UlLi 5
f Jill «
ilifj

iS D50

Data/Print

DEPT. KB. BOX 903. FARGO. N.D. 58107

y/ 0 Reader Service— see page 227

Microcomputing, October 1979 101

Steve Tabler

1573 South Sherman Street
Denver CO 80210

Calendar Program

You say pinup calendars are passe? Polish up your pin-outs and program the years ahead.

T his calendar program was written in Southwest Technical Prod-
ucts 8K BASIC version 2.3. The system used was the SWTP
M6800/2. It had 12K of static RAM memory. A video terminal and Kan-
sas City Standard cassette interface shared port 1, and a 72-column
printer was located at port 7 at the time I wrote the program.*

n * K X L

Sample run.

0001 REM CALENDAR PROGRAM WRITTEN IN SWTPC 8K BASIC VERSION 2.3

0002 REM WRITTEN BY STEVE TABLER JULY 24, 1978

0003 REM WILL RUN IN 12K MEMORY SYSTEM.

0004 REM PROGRAM DOES SINGLE MONTH OR FULL YEAR .

0005 REM INSTRUCTIONS APPEAR ON CONTROL TERMINAL.

0006 REM LINE 8000 SETS WIDTH OF CALENDAR, PORT NUMBER OF PRINTER, COLUMNS

0007 REM PRINTER HAS AVAILABLE.

0008 REM CHANGE THE 28 IN LINE 8010 TO 29 FOR LEAP YEARS.

0009 REM PROGRAM SETS PRINTER TO PORT 7 UNLESS MODIFIED.

0010 DIM A(12),R$(12),B$(7)

0015 X-l

0020 PRINT "IS THIS A FULL YEAR" INPUT Y$

0030 IF LEFT$ (Y$ , 1 )»" Y" THEN X-13:M-1
0035 IF X-l 3 THEN 50
0040 GOSUB 800

0050 PRINT "WHAT DAY DOES THE MONTH/YEAR START?"

0051 PRINT "(TYPE NUMBER)"

0060 PRINT "1-SUNDAY"

0070 PRINT "2-MONDAY"

0080 PRINT "3-TUESDAY"

0090 PRINT "4-WEDNESDAY"

0100 PRINT "5-THURSDAY"

0110 PRINT "6-FRIDAY"

0120 PRINT "7-SATURDAY"

0130 INPUT D

0140 READ W,P,Z
0145 LINE-7.

0150 C-W/8

0160 FOR 1-1 TO 12: READ A(I):NEXT. I
0170 FOR C2=l TO X
0180 FOR S-l TO 12: READ R$(S);NEXT S
0190 PRINT#P,TAB(3);

0199 LET T2-W/2-9

0200 FOR J-l TO 3+T2 :PRINT#P,"-"; :NEXT J
0210 PRINT#P,R$ (M) ;

0220 FOR J-l TO 3+T2:PRINT#P,"»" ; :NEXT J

0225 PRINT#P:PRINT#P

0230 FOR S-l TO 7 :READ B$(S):NEXT S

0240 FOR U-l TO 7

0245 PRINT#P,TAB(U*C);B$(U);

0250 NEXT U
0255 PRINT#P:PRINT#P
0310 FOR U-l TO 7
0315 PRINT#P,TAB(U*C);

0319 IP C3>0 THEN 325

0320 IF U^D THEN 340
0325 C3-C3+1

0330 PRINT #P,C3;

0335 IF C3-A(M) THEN 600
0340 NEXT U

0345 PRINT #P: PRINT #P

0355 GOTO 310

0360 NEXT C2

0600 IF M-12 THEN 9999

0610 PRINT #P: PRINT # P

0620 M-M+l : C3-0 : D-U+l

0630 RESTORE

0635 IF D*8 THEN D-l

0640 IF X-13 THEN 140

0650 STOP

0800 PRINT "WHICH MONTH" : PRINT" (TYPE NUMBER)"

0810 PRINT "i-JANUARY"

0820 PRINT "2-FEBRUARY"

0830 PRINT "3-MARCH"

0840 PRINT "4-APRIL"

0850 PRINT "5-MAY"

0860 PRINT "6- JUNE"

0870 PRINT "7- JULY"

0880 PRINT "8-AUGUST"

0890 PRINT "9-SEPTEMBER"

0900 PRINT "10- OCTOBER"

0910 PRINT "ll-NOVEMBER"

0920 PRINT "12-DECEMBER"

0930 INPUT M
0940 RETURN
8000 DATA 50,7,120

8010 DATA 31,28,31,30,31,30,31,31,30,31,30,31

8040 DATA -JANUARY- , -FEBRUARY , — MARCH— .--APRIL— ,— MAY— -, — JUNE-

8050 DATA ---JULY-- .--AUGUST- .SEPTEMBER, -OCTOBER -

8055 DATA -NOVEMBER, -DECEMBER

8060 DATA S ,M,T,W,T,F,S

9999 END

Program listing.

102 Microcomputing, October 1979.

CIRCUIT BREAKER PRICE SLASHING

16K MEMORY UPGRADE KITS

DISK OPERATING SYSTEMS

•300 NS for TRS-80* $69.00

•250 NS for TRS-80*, Apple II, Sorcerer (specif y)$75.00
•200 NS for TRS-80*, Apple II, Sorcerer (specif y)$85.00

All kits complete with jumpers and instructions.

90 DAY WARRANTY

LETTER QUALITY
HIGH SPEED PRINTER

NEC Spinwriter

$2679.00

Includes TRS-80* interface software, quick change print fonts,
55 cps, bidirectional, high resolution plotting, graphing,
proportional spacing. 90 DAY WARRANTY.

Radio Shack DOS 2.2— No key bounce $14.95

NEWDOS by Apparat t No key bounce $49.95

Enhancements to DOS 2.1, enhanced RENUM, BASIC varia-
bles and constants locater, enable/disable passwords, auto-
matic validity check for disk write, load and save up to 30%
faster, diskette space allocated in 1-granule increments
instead of 2, BASIC open “E” allows additions to sequential
files, “JKL" option outputs screen display to printer, DOS com-
mands executable from BASIC, one-step entry to BASIC from
DOS. LIST, EDIT, and DELETE abbreviations. BASIC scrolling.

NEWDOS “PLUS” by Apparat t $99.95

NEWDOS plus the following functions: enhanced DIRCHECK
command, improved EDITOR, ASSEMBLER, DISASSEMBLER.
SUPERZAP. Machine language RELOCATOR, LEVEL I on disk.

DOS 3.0 by the original author of 2.1 $49.95

No key bounce. Check EOF, write EOF, SEEK, REREAD,
REWRITE, LOC, variable length records, SKIP, disk logging of
messages, BOOT, CHAIN, PAUSE, PURGE, SET, RESET,
ROUTE. RUN and LOAD for 1 drive system. XFER, FORMAT
w/o ERASE. DIR from BASIC, PATCH, LINK, user defined keys,
key auto repeat, upper and lower case driver, shift lock, RS-232
drivers, MULTI PROTOCOL COMMUNICATIONS.

TRS-80* COMPATIBLE HARDWARE DISKETTE TRS-80*

DISK DRIVES BUSINESS SOFTWARE BY SBSG

More capacity than Radio Shack 35 track (80K Bytes) drives.
Fully assembled and tested. Ready to plug-in and run the
moment you receive it. Can be intermixed with each other and
Radio Shack drive on same cable. TRS-80* compatible silver

enclosure. 90 DAY WARRANTY.

CCI-1 00 40 Track (1 02K Bytes) $324.00

CCI-200 77 Track (197K Bytes) $594.00

2 Drive Cable $25.00

4 Drive Cable $35.00

PRINTERS

779 CENTRONICS TRACTOR FEED PRINTER $1050.00

Same as Radio Shack line printer

701 CENTRONICS TRACTOR FEED PRINTER $1499.00

2V2 times faster than line printer, full 132 characters,
carriage bell tone.

PI CENTRONICS PRINTER $399.00

Same as Radio Shack quick printer.

CENTRONICS CABLE for TRS-80* $39.00

For use with above printers.

TRS-80* COMPLETE SYSTEMS

TRS-80* LEVEL II-4K $540.00

TRS-80* LEVEL II-16K with 10 key keypad $799.00

TRS-80* Expansion Interface $269.00

TRS-80* RS-232-C Interface $84.00

MISCELLANEOUS

TRS-232 by SMALL SYSTEMS SOFTWARE RS-232-C or
Teletype Current Loop output from cassette port. $49.00

CAT MODEM $169.00

Originate and answer same as Radio Shack Telephone
Interface II.

DISKETTES: Verbatim
Dysan

C-10 CASSETTES

10 for $32.00
5 for $25.00
10 for $9.00

Free enhancements and upgrades to registered owners for the
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Fully Interactive Accounting Package: Requires 2,3, or 4
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Complete package (Requires 3 or 4 drives) $389.00

Individual Modules (Require 2 or 3 drives) $99.00

Inventory II: Requires 2 or 3 drives. Handles up to 1000 items
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Mailing List Name & Address II System: Requires 2 drives. Use
with Electric Pencil files for automatic insertion of name,
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Menu driven. Includes enter, delete, update, search, extract,
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600 names in 7 minutes. 40 page manual. Zip code sort is
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Intelligent Terminal System ST-80 III: Enables a TRS-80* to act
as a dial-up terminal on any standard time sharing network.
Provides a TRS-80* with control key, ESC Key, Repeat Key,
Rub Out Key, Break Key, full upper and lower case support,
selectable printer output and program selectable transmission
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Note: SBSG maintains a time-sharing computer where you can
dail-up and leave your problems, 24 hours, 7 days a week.

Word Processing System: The Electric Pencil from Michael
Shrayer. Diskette $150.00

Cassette $99.00

File Management System: For specialized storage needs.
Sorts files in ascending or descending order on 3 separate
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phone numbers, names, slides, albums. Selectively totals
numeric and dollar fields. Display and print capability. $49.00

MMSFORTH System Diskette: A complete professional
FORTH system. Requires 16K TRS-80* and 1 drive. $65.95
Book on FORTH. Contains documentation. $15.00

The CPU SHOP -

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TO ORDER CALL 617/242-3350

Hours: 10 AM - 6 PM (EST) Monday - Saturday

*TRS-80 is a Tandy Corporation Trademark t Requires Radio Shack TRSDOS

39 Pleasant Street, Dept. K-10
Charlestown, Massachusetts 02129

Freight collect, F.O.B.

Charlestown

Massachusetts residents add

5% sales tax

Dealer Inquiries Invited

iS Reader Service— see page 227

Microcomputing, October 1979 103

Four More Commands
for SSB DOS

BFD-68 disk users can easily add CLEAR, MOVE, LOCATE and DUMP to their repertoire.

Terry Perdue
1470 Wilson Road
St. Joseph Ml 49085

I have been using Smoke Signal
Broadcasting’s popular
BFD-68 disk system with my
SWTP computer for several
months now and don’t know
how I ever got along without it.

The commands furnished with
the operating system allow a
great deal of flexibility, and the
additional commands available
on their users’ group library
disk, UGLY 0, make the system a
pleasure to use.

Presented here are four addi-
tional commands that I have
found helpful. The operations
they perform are associated
with the contents of RAM. They
execute quickly and print an er-

SDUhP E7 135

01 2345478?

A B C D E F

OOFO

7F 80 01

FE 07 00 FF 80 00

0*FO

FE 04 FE 08 FF 04 FE A4 00 4D 27 A4 85 80 27 04

Of 00

85 40 27 20 20 19 81 7F 27 IF B7 07 04 FE 07 03

0110

5C B4 07 04 09 27 DO 4A 24 FA F7 80 00 20 FI BP

0120

04 5D 20 C3 BP 02 27 20 C7 7F

80 01 CE 00 04 FF

0130

80 00 20 H9 81 IB

SCLEAR, 102, IOC

SHUHP F7,135

012345478?

A B C D E F

OOEO

7F 80 01

FE 07 00 FF 80 00

OOFO

FE 04 FE 08 FF 04 FE A4 00 4D 27 A4 85 80 27 04

0100

85 40 00 00 00 00 00 00 00 00 00 00 00 FE 07 03

OHO

5C B4 07 04 09 27 DO 4A 24 FA F7 80 00 20 FI BD

0120

04 5D 20 C3 BP 02 27 20 C7 7F 80 01 CE 00 04 FF

0130

80 00 20 D9 81 IB

SHOVE

130 135 105

SPUMP E7 135

012345478?

A B C D E F

OftEO

7F 80 01

FE 07 00 FF 80 00

OOFO

FE 04 FE 08 FF 04 FE A4 00 4D

27 A4 85 80 27 04

0100

85 40 00 00 00 80 00 20 P9 81

IB 00 00 FE 07 03

0110

5C B4 07 04 09 27 DO 4A 24 FA

F7 80 00 20 FI BD

0120

04 5D 20 C3 BD 02 27 20 C7 7F

80 01 CE 00 04 FF

0130

80 00 20 D9 81 IB

8 , LOCATE 9000 E 7 135

FOUND AT:

OOEE,

0105, 01 IB, 0130

Example 1.

ror message if the command is
improperly formatted.

The Commands

The CLEAR command clears
the specified block of memory.

The MOVE command will
move intact the contents of the
specified block of memory any-
where else in memory. An entire
28 K can be moved almost in-
stantaneously. The routine
checks the direction of the move
to determine from which end of
the block the move should be
made to avoid errors when the
address ranges overlap.

The LOCATE command will
search the specified block of
memory for any hex string of
characters, from one to over 50
bytes in length, and print each
address where the string exists.
If the string does not exist
within that range, “NOT
FOUND” will be printed.

The DUMP command outputs
the contents of the specified
block of memory in a 16-bytes-
per-line format. Each line begins
with the address of the first
position on that line, which is
always an integral multiple of
16. This allows the columns to

be headed for easier reading.

Consult the listings for the
proper format of each com-
mand, noting that <SA> is the
starting address, <EA> is the
ending address (inclusive) and
<DA> is the destination ad-
dress. Example 1 illustrates the
results obtained.

These routines have been
assembled assuming the DOS is
located at $7000. If yours is at
$D000, all program references to
$7000 block addresses will need
to be changed to reference the
corresponding addresses in the
$D000 block.

Note: Since these commands
occupy the transient program
area (TPA), which exists within
the monitor, the SAVE.BLD pro-
gram furnished with the DOS
must be loaded (using the resi-
dent GET command) before
SAVEing the file. If you fail to do
this or if you use any other tran-
sient command, such as LIST,
after keying in the program and
before SAVEing it, you will wipe
out the program you intended to
save. See the manual for details.

I hope you will find that these
commands add to the utility of
your disk system. ■

Listing 1. CLEAR command.

00010

NAM

CLEAR. $

00030

* COMMAND FORMAT: SCLEAR , <SA> , <EA>

00050

* WRITTEN BY

TERRY PERDUE 7-78

00070

OPT

00090

7080

TPA ECHJ

$7080

00100

7283

Z WARMS ECHJ

$7283

00110

729D

ZDIE ECHJ

$72?D

00120

72A0

ZGETHN EQU

$72A0

00140 7080

ORG

TPA

104 Microcomputing, October 1979

00160

7080

7 2 AO

JSR

ZGETHN

GET START ADR.

00450

70CA

BB 71 3F

ADD A

DESTIN+1

GET

00170

7083

BOS

ADRERR

NON HEX

00460

70CD

B 7 71 3F

STA A

DESTIN+1

HIGHEST

00180

7085

TST B

00470

70D0

B 6 7140

LDA A

NUMBER

ADDRESS

00190

7086

BEQ

ADRERR

NO ST. ADR.

00480

70D3

B9 71 3E

ADC A

DESTIN

00200

7088

70D4

STX

START

SAVE ST. ADR.

00490

70D6

B7 713E

STA A

DESTIN

DESTINATION

00210

708B

72 AO

JSR

ZGETHN

GET END ADR.

00500

70D9

FE 71 3E

LDX

DESTIN

AND

00220

708E

BCS

ADRERR

NON HEX

00510

70DC

DEX

START

00230

7090

TST B

00520

70DD

FF 71 3E

STX

DESTIN

THERE

00240

7091

BEQ

ADRERR

NO END ADR.

00530

70E0

FE 71 3C MOVEUP LDX

END

POINT TO BYTE

00250

7093

70D6

STX

END

SAVE END ADR.

00540

70E3

A6 00

LDA A

GET IT

00260

7096

70D7

LDA B

END+1

00550

70E5

DEX

DEC. FROM POINTER-

00270

7099

70D5

SUB B

START+1

00560

70E6

FF 71 3C

STX

END

SAVE IT

00280

7090

70D6

LDA B

END

00570

70E9

FE 71 3E

LDX

DESTIN

GET DESTINATION

00290

709F

70D4

SBC B

START

00580

70EC

A7 00

STA A

PUT BYTE THERE

00300

70A2

BMI

ADRERR

00590

70EE

DEX

ICC. 'TO' POINTER

00310

70A4

70D6

LDX

END

ADD ONE

00600

70EF

FF 71 3E

STX

DESTIN

SAVE IT

00320

70A7

I NX

00610

70F2

FE 7140

LDX

NUMBER

ICC. THE

00330

70A8

70D6

STX

END

END ADR.

00620

70F5

DEX

BYTE COUNTER

00340

70AB

CMP A

HtD

LAST DELIM. A CR.?

00630

70F6

27 31

BEQ

DONE

IF ZERO, DONE

00350

70AB

BNE

ADRERR

00640

70F8

FF 7140

STX

NUMBER

SAVE IT

00360

70AF

70D4

LDX

START

00650

70FB

20 E3

BRA

MOVEUP

GO DO AGAIN

00370

70B2

CLR A

00660

70FD

BD 72A0 GETADR

JSR

ZGETHN

GET AN ADR. FROM IN. BUFFER

00380

70B3

70D6 ZERO

CPX

END

LAST ADR.?

00670

7100

25 04

BCS

PERROR

NON HEX

00390

70B6

BEQ

DONE

00680

7102

TST B

00400

70B8

STA A

CLR IT

00690

7103

27 01

BEQ

PERROR

NO ADR.

00410

70BA

INX

POINT TO NEXT ADR.

00700

7105

RTS

RETURN

00420

70BB

BRA

ZERO

GO CLEAR IT

00710

7106

CE 712C PERROR

LDX

NERROR

00430

70BD

7283 DONE

JMP

ZUARMS

00720

7109

7E 729D

JMP

ZDIE

00440

70C0

70C6 ADRERR LDX

NERRNSG

00730

71 OC

FE 71 3A MOVEDN LDX

START

POINT TO BYTE

00450

7003

729D

JMP

ZDIE

00740

710F

A6 00

LDA A

GET IT

00750

7111

INX

INC. 'FROM POINTER-

00470

70C6

ERRMSG FCC

'ADDRESS ERROR'

00760

7112

FF 713A

STX

START

SAVE IT

70C7

00770

7115

FE 71 3E

LDX

DESTIN

GET DESTINATION

70C8

00780

7118

A7 00

STA A

PUT BYTE THERE

7009

00790

71 1A

INX

INC. 'TO' POINTER

70CA

00800

71 IB

FF 71 3E

STX

DESTIN

SAVE IT

70CB

00810

71 IE

FE 7140

LDX

NUMBER

DEC. THE

70CC

00820

7121

DEX

BYTE COUNTER

70CB

00830

7122

27 05

BEQ

DONE

IF ZERO, DONE

70CE

00840

7124

FF 7140

STX

NUMBER

SAVE IT

70CF

00850

7127

20 E3

BRA

MOVEDN

GO DO AGAIN

70D0

00860

7129

7E 7283

DONE

JMP

ZUARMS

70D1

70D2

00880

71 2C

ERROR

FCC

'ADDRESS ERROR'

00480

70D3

FOB

7^2D

71 2E

00500

70D4

0002

START

RMB

71 2F

00510

70D6

0002

END

RMB

7130

7131

00530

END

7132

7133

7134

7135

Listinq 2. MOVE command.

7136

7137

7138

00010

NAM

MOVE . $

00890

7139

FCB

00030

* COMMAND FORMAT:

00910

71 3A

0002

START

RMB

00040

SMOVE , <SA> , <EA> , <DA>

00920

71 3C

0002

END

RMB

00930

713E

0002

DESTIN RMB

00060

* URITTEN BY

TERRY PERDUE 7-78

00940

7140

0002

NUMBER RMB

00950

7142

0002

XTEMP

RMB

00080

OPT

00970

END

00100

7080

TPA

EQU

♦7080

00110

7283

ZUARMS

EQU

♦7283

00120

729D

ZDIE

EQU

♦729D

00130

72A0

ZGETHN

EQU

♦72A0

Listing 3. LOCA TE command.

00150 7080

ORG

TPA

00010

NAM

LOCATE. ♦

00170 7080 8D

BSR

GETADR

GET START ADR.

00180 7082 FF

71 3A

STX

START

SAVE IT

00030

* COMMAND FORMAT:

00190 7085 8D

BSR

GETADR

GET END ADR.

00040

3L0CATE. <HEX STRING>,<SA>,<EA>

00200 7087 FF

7130

STX

END

SAVE IT

00210 708A 8D

BSR

GETADR

GET DESTINATION ADR.

00060

* URITTEN BY

TERRY PERDUE 7-78

00220 708C FF

71 3E

STX

DESTIN

SAVE IT

00230 708F

CMP A

*♦!(

LAST DELIM. A CR.?

00080

OPT

00240

7091

BNE

PERROR

00250 7093 B6

71 3D

LDA A

END+1

GET DIFFERENCE

00100

7080

TPA

EQU

17080

00260

7096 BO

71 3B

SUB A

START+1

BETWEEN

00110

7283

ZUARMS

EQU

$7283

00270 7099 B7

7141

STA A

NUMBER+1

END ADR.

00120

7286

OUTEEE

EQU

♦7286

00280

7090 B6

7130

LDA A

END

AND START

00130

7297

ZGNCHR

EQU

♦7297

00290

709F

71 3A

SBC A

START

ADR.

00140

729D

ZDIE

EQU

♦729D

00300

70A2

BMI

PERROR

00150

72A0

ZGETHN

EQU

♦72A0

00310 70A4 B7

7140

STA A

NUMBER

ADD ONE

00160

72A6

ZOUTST

EQU

♦72A6

00320 70A7

7140

LDX

NUMBER

TO GET

00170

72AF

ZOUTHA

EQU

♦72AF

00330

70 A A

INX

LENGTH

00180

72FC

BUFPTR

EQU

♦72FC

00340

70AB

7140

STX

NUMBER

OF BLOCK

00350 70AE B6

71 3B

LDA A

START+1

FIND OUT

00200

7080

ORG

TPA

00360 70B1

71 3F

SUB A

DESTIN+1

WHICH

00370

70B4

7143

STA A

XTEMP+1

WAY TO

00220

7080

FE 72FC

LDX

BUFPTR

GET ADR. OF DELIM. PREC. STRI

00380 70B7 B6

71 3A

LDA A

START

MOVE BLOCK -

00230

7083

FF 71A9

STX

STGBEG

SAVE IT

00390 70BA B2

713E

SBC A

DESTIN

DETERMINES

00240

7086

BD 72A0

JSR

ZGETHN

FIND NEXT DELIM.

00400

70BD B7 7142

STA A

XTEMP

WHICH END

00250

7089

24 03

BCC

++5

00410 7000 FE

7142

LDX

XTEMP

TO WORK FROM

00260

708 B

7E 7110

JMP

STGERR

NON HEX CHAR. IN STRING

00420 70C3 27 64

BEQ

DONE

NO MOVE REQ'D

00270

708E

TST B

00430 70C5

BPL

MOVEDN

MOVE DOWN OR -

00280

708F

27 7F

BEQ

STGERR

NO HEX CHAR. IN STRING

00440 70C7 B6

7141

LDA A

NUMBER+1

UP:

00290

7091

FE 72FC

LDX

BUFPTR

GET ADR. OF DELIM. FOLL. STRI

Microcomputing, October 1979 105

00300

7094

71 AB

STX

STGEND

SAVE IT

7178 56

00310

7097

72A0

JSR

ZGETHN

GET START ADR.

7179 41

00320

709A

BCS

ADRERR

NON HEX

71 7A 4C

00330

709C

TST

717B 49

00340

709D

BEG

ADRERR

NO SR. ADR.

717C 44

00350

709F

71B2

STX

START

SAVE ST. ADR.

717D 20

00360

70A2

DEX

71 7E 53

00370

70A3

71 AF

STX

MPTR1

START LOC. MINUS ONE

717F 54

00380

70A6

72A0

JSR

ZGETHN

GET END ADR.

7180 52

00390

70A9

BCS

ADRERR

NON HEX

7181 49

00400

70AB

TST

7182 4E

00410

70AC

BEG

ADRERR

NO END ADR.

7183 47

00420

70AE

71B4

STX

END

SAVE END ADR.

01290 7184 00

FCB

00430

70B1

71B3

LDA

ST ART ♦ 1

01300 7185 41

PADERR FCC

"ADDRESS

ERROR"

00440

70B4

71B5

SUB

END+1

7186 44

00450

70B7

71B2

LDA

START

7187 44

00460

70BA

71B4

SBC

END

7188 52

00470

70BD

BPL

ADRERR

7189 45

00480

70BF

71B4

LDX

END

ADD ONE

718A 53

00490

70C2

INX

71 BB 53

00500

70C3

71B4

STX

END

END ADR.

71 8C 20

00510

70C6

CHP

tt$D

FINAL DELIM. A CR?

718D 45

00520

70C8

BNE

ADRERR

71 8E 52

00530

70CA

71A9

TRYAGN LDX

STGBEG

ADR. OF DELIM. PREC. STRING

718F 52

00540

70CD

72FC

STX

BUFPTR

POINT TO IT

7190 4F

00550

70D0

71 AF

LDX

HPTR1

ADVANCE POINTER

7191 52

00560

70D3

INX

AND START

01310 7192 00

FCB

00570

70D4

71 AF

STX

MPTR1

COMPARING

01320 7193 46

FNDMSG FCC

"FOUND AT:"

00580

70D7

71 AD

CONTIN STX

MEMPTR

CONTINUE MATCHING

7194 4F

00590

70DA

LDA

GET CHAR. FROM MEMORY

7195 55

00600

70DC

7 1 B 1

STA

TEMP

7196 4E

00610

70DF

7297

JSR

ZGNCHR

MS NIB. OF ASCII CHAR. FROM S

7197 44

00620

70E2

72FC

LDX

BUFPTR

HAS LAST CHAR. FROM STRING

7198 20

00630

70E5

71 AB

CPX

STGEND

BEEN MATCHED?

7199 41

00640

70E8

BEG

FOUND

SUCCESS!

719A 54

00650

70EA

BSR

ASCTHX

CONVERT IT TO HEX

719B 3A

00660

70EC

ASL

01330 719C 00

FCB

00670

70ED

ASL

01340 719D 4E

NFMSG FCC

"NOT FOUND'

00680

70EE

ASL

719E 4F

00690

70EF

ASL

719F 54

00700

70F0

TAB

71 AO 20

00710

70F1

7297

JSR

ZGNCHR

LS NIBBLE

71A1 46

00720

70F4

72FC

LDX

BUFPTR

71A2 4F

00730

70F7

71 AB

CPX

STGEND

71 A3 55

00740

70FA

BEG

STGERR

STRING CONTAINED A HALF-BYTE

71A4 4E

00750

70FC

BSR

ASCTHX

CONVERT TO HEX

71A5 44

00760

70FE

ABA

PACK TO FORM HEX BYTE

01350 71 A6 OAOO

FDB

♦OAOO

00770

70FF

7 1 B 1

LDA

TEMP

CHAR. FROM MEMORY

00780

7102

71 AD

MATCHK LDX

MEMPTR

ADVANCE AS LONG AS

01370 71A8 00

F0UND1 FCB

00790

7105

71B4

CPX

END

MATCHES OCCUR UNLESS

01380 71A9 0002

STGBEG RMB

00800

7108

BEG

DONE

REACH LAST ADR. UITHOUT

01390 71 AB 0002

STGEND RMB

00810

71 OA

INX

COMPLETE MATCH

01400 71 AD 0002

MEMPTR RMB

00820

71 OB

1 1

CBA

COMPARE BYTES

01410 71 AF 0002

MPTR1 RMB

00830

71 OC

BNE

TRYAGN

NO MATCH

01420 7 1 B 1 0001

TEMP RMB

00840

71 OE

BRA

CONTIN

MATCHED - CHECK NEXT BYTE

01430 71B2 0002

START RMB

00850

7110

7176

STGERR LDX

NPSTERR

01440 71B4 0002

END RMB

00860

7113

729D

JMP

ZDIE

00870

7116

7185

ADRERR LDX

NPABERR

01460

END

00880

7119

729D

JHP

ZDIE

rnkji irDT

00890

71 1 C

ASCTHX SUB

#♦30

CONVERT

00900

71 1 E

CMP

ASCII CHAR.

00910

7120

BLE

RETURN

IN STRING

Listing 4. DUMP command.

00920

7122

SUB

TO HEX

00930

7124

RETURN RTS

00940

7125

71A8

FOUND LDA

F0UND1

IF FIRST FIND,

00010

NAM

DUMP.!

00950

7128

BEG

OUTFND

OUTPUT "FOUND AT:'

00960

712A

CMP

#$A

IF TEN ADR. ON LINE,

00030

* COMMAND FORMAT: *DUMP,<SA>,<EA>

00970

712C

BEQ

NULINE

START NEU LINE

00980

712E

LDA

•'»

ELSE PRINT A COMMA,

00050

* WRITTEN BY

TERRY PERDUE 7-78

00990

7130

7286

JSR

OUTEEE

01 000

7133

LDA

#♦20

AND A SPACE,

00070

OPT

01 010

7135

7286

JSR

OUTEEE

01020

7138

BRA

OUTADR

THEN NEXT ADR.

00090 7080

TPA EGU

♦7080

01030

713A

71A8

NULINE CLR

F0UND1

00100 7283

ZUARMS EGU

♦7283

01040

71 3D

BSR

CRLF

00110 7286

OUTEEE EGU

♦7286

01050

713F

71A8

OllTADR INC

F0UND1

COUNT ADR.S PER LINE

00120 729D

ZDIE EQU

♦729D

01060

7142

71 AF

LDX

#MPTR1

POINT TO ADR.

00130 72A0

ZGETHN EQU

♦72 AO

01070

7145

72AF

JSR

ZOUTHA

OUTPUT IT

00140 72AC

ZOUTHX EQU

♦72AC

01080

7148

BRA

TRYAGN

LOOK FOR MORE OF SAME STRING

00150 72AF

ZOUTHA EGU

♦72AF

01090

714A

OUTFND BSR

CRLF

01 100

714C

7193

LDX

#FNDHSG

"FOUND AT:'

00170 7080

ORG

TPA

OHIO

714F

72A6

JSR

ZOUTST

01120

7152

BSR

CRLF

00190 7080 BD 72A0

JSR

ZGETHN

GET START ADR.

01130

7154

BSR

CRLF

00200 7083 25 7A

BCS

PERROR

NON HEX

01140

7156

BRA

OUTADR

00210 7085 5D

TST B

01150

7158

DONE BSR

CRLF

00220 7086 27 77

BEQ

PERROR

NO START ADR.

01160

715A

71A8

TST

F0UND1

00230 7088 FF 7158

STX

MEMPTR

SAV ST. ADR.

01170

715D

BEQ

NOFIND

STRING NEVER FOUND

00240 708B BD 72A0

JSR

ZGETHN

GET END ADR.

01180

715F

7283

JMP

ZUARMS

00250 708E 25 6F

BCS

PERROR

NON HEX

01190

7162

719D

NOFIND LDX

#NFMSG

"NOT FOUND"

00260 7090 5D

TST B

01200

7165

72A6

JSR

ZOUTST

00270 7091 27 6C

BEG

PERROR

NO END ADR.

01210

7168

7£

7283

JMP

ZUARMS

00280 7093 FF 71 5A

STX

END

SAVE END ADR.

01220

716B

CRLF LDA

#♦0

00290 7096 F6 71 5B

LDA B

END+1

01230

716D

7286

JSR

OUTEEE

00300 7099 FO 7159

SUB B

NEMPTR+1

01240

7170

LDA

♦ ♦A

00310 709C F6 71 5A

LDA B

END

01250

7172

7286

JSR

OUTEEE

00320 709F F2 7158

SBC B

MEMF'TR

01260

7175

RTS

00330 70A2 2B 5B

BMI

PERROR

00340 70A4 FE 71 5A

LDX

END

ADD ONE

01280

7176

PSTERR FCC

'INVALID

STRING'

00350 70A7 08

INX

7177

00360 70A8 FF 71 5A

STX

END

END ADR.

106 Microcomputing, October 1979

00370

70AB

CMP

#$D

LAST DELIM. A CR.?

00380

70AD

BNE

PERROR

00390

70AF

BSR

CRLF

PRINT HEADING

00400

70B1

BSR

0UT2S

00410

70B3

BSR

0UT2S

00420

70B5

LDA

START WITH 0

00430

70B7

C0NTIN

BSR

0UT2S

AND PRINT THRU F

00440

70B9

TBA

00450

70BA

7286

JSR

OUTEEE

00460

70BD

CMP

#'9

PRINTED 9 YET?

00470

70BF

BNE

LETTER

00480

70C1

LDA

#♦40

IF SO, NEED A THRU F

00490

70C3

LETTER

CMP

#'F

00500

70C5

BEQ

NXTLIN

00510

70C7

INC

00520

70C8

BRA

CONTIN

00530

70CA

NXTLIN

BSR

CRLF

00540

70CC

LDA

#53

NEXT LINE OF HEADING

00550

70CE

DASH

LDA

TO BE 53 DASHES

00560

70D0

7286

JSR

OUTEEE

00570

70D3

DEC

COUNT THEM

00580

70D4

BNE

DASH

00590

70D6

BSR

CRLF

00600

70R8

7159

LDA

MEMPTR+1

GET LS BYTE OF ST. ADR.

00610

70DB

PSH

SAVE IT

00620

70DC

TAB

00630

70BD

AND

MfFO

MAKE IT -0

00640

70DF

7159

STA

MEMPTR+1

OUTPUT

00650

70E2

BSR

OUT ADR

THAT ADR.

00660

70E4

PUl

00670

70E5

7159

STA

MEMPTR+1

RESTORE ADR. POINTER

00680

70E8

SBA

DIFFERENCE IS NUMBER

00690

70E9

TAB

OF BYTES TO SKIP

00700

70EA

PSH

SAVE FOR LATER

00710

70€B

SKIP

TST

DONE SKIPPING?

00720

70EC

BEQ

READY

GO DO YOUR THING

00730

70EE

BSR

0UT2S

00740

70F0

BSR

OUT IS

00750

70F2

DEC

00760

70f3

BRA

SKIP

00770

70F5

7158

READY

LDX

MEMPTR

GET START ADR.

00780

70F8

PUL

NUMBER OF BYTES SKIPPED

00790

70F9

LDA

#♦10

FROM TOTAL PER LINE

00800

70FB

SBA

GIVES NUMBER LEFT TO PRINT

00810

70FC

TAB

IN FIRST LINE

00820

70FD

BRA

GO START TO OUTPUT LINES

00830

7 OFF

7148

PERR0R

LDX

#ERR0R

00840

7102

729D

JSR

ZDIE

00850

7105

NULINE

BSR

CRLF

START NEU LINE

00860

7107

BSR

OUT ADR

WITH ADDRESS

00870

7109

LDA

#♦10

NO. OF BYTES PER LINE

00880

71 0B

72AC

JSR

ZOUTHX

OUTPUT THE BYTE

00890

710E

BSR

OUT IS

00900

7110

INX

00910

7111

7158

STX

MEMPTR

00920

7114

715A

CPX

END

IF NOT DONE,

00930

7117

BEQ

DONE

00940

7119

DEC

DEC. BYTE POINTER

00950

711 A

BNE

AND CONTINUE. IF 16 BYTES,

00960

71 1C

BRA

NULINE

START NEU LINE

00970

71 IE

DONE

BSR

CRLF

00980

7120

7283

JMP

ZUARMS

00990

7123

01JT2S

LDA

#♦20

01000

7125

7286

JSR

OUTEEE

01010

7128

OUT IS

LDA

#♦20

01020

71 2A

7286

JSR

OUTEEE

01030

71 2D

RTS

01040

71 2E

CRLF

LDA

#♦0

01050

7130

7286

JSR

OUTEEE

01060

7133

LDA

#^A

01070

7135

7286

JSR

OUTEEE

01080

7138

RTS

01090

7139

7156

OUT ADR

STX

XSAVE

SAVE X

01100

713C

7158

LDX

#MEMPTR

POINT TO LOC. OF ADR.

OHIO

71 3F

72AF

JSR

ZOUTHA

OUTPUT IT

01120

7142

7156

LDX

XSAVE

RESTORE X

01130

7145

BSR

0UT2S

01140

7147

RTS

01160

7148

ERROR

FCC

'ADDRESS ERROR"

7149

71 4A

71 4B

71 4C

71 4D

71 4E

71 4F

7150

7151

7152

7153

7154

01170

7155

FCB

01190

7156

0002

XSAVE

RMB

01200

7150

0002

MEMPTR

RMB

01210

715A

0002

END

RMB

01230

END

STIK

IT....
••to your

That's right! Esmark's VIDIET-STIK light pen now has the TOS-80
CONNECTION for LEVEL I & II. Your 4K to 48K TRS-80 System will
come alive under your VIDIET-STIK within minutes of its arrival.
That's because there are no wires to solder or traces to cut.
Your up and running as fast as you can plug the interface into
your system's cassette EAR- jack, CLQAD our custom LIGHT-WAVE
demonstration software and RUN. And because the interface has a
plug for your recorder, you won't have to unplug it again when
loading your other software tapes. The inteface allows them to
pass right thru whenever your not using the pen. Its' exclusive
"switched tip" design means the pen's electrically isolated from
your system when it's not in use. Just point & press! It's that
simple... Plug, CLOAD and RUN. And have we got the softvrare for
you to RUN with! Our demonstration tape includes a calibration
program (used to adjust the CRT's brightness and contrast) plus
STIK-TAC-TOE, AWARI and TOWERS. Two challanging games and a
puzzle that will keep grownups and children Stik'ing it to
your TRS-80 for hours. And there are instructions provided so
you can begin writing your own light pen programs (lightware)
for fun or profit (Level II). Or, just sit back and enjoy our
LIGHT-WAVE tapes each month. Esmark's unmatched commitment to
lightware can bring you up to five new games, puzzles, drills
& educational quizes or simulations each month. This month's
LIGHT-WAVE release is:

LIGHT-PAK 2
(LEVEL II)

- LIGHTPEG (4 peg- jump puzzles)

ENDRUN (Othello with a 'twist')

LIFE9 (Conway's LIFE with mutations)

Price: $ 19.95 (including postage & handling)

Order yours now and we'll include a free copy of FLASHBACK,
Esmark's newsletter dedicated to the latest news in lightvare
applications. And, don't forget to tell your friends. The
VIDIET-STIK can also be ordered for use on most other micro
systems using the following processor chips:

8080 Z80 6800 6502

All that's required is a standard cassette jack leading to
Ground and a readable single bit input port. Driver software
is provided along with instructions for writing lightware
applications. And tell your local Dealer that Esmark's got
a Dealer package he won't want to miss out on. Delivery is
3 to 6 weeks from receipt of your order. C.O.D. 's are $3.00
extra but will be shipped within two weeks. All prices are
F.O.B. Mishawaka, Indiana. Indiana residents add 4% state
sales tax.

ALSO COMING FROM E94ARK:

[ ] TRS-80 Printer Interface (Cassette EAR-jack interface for
all RS232 printers. Includes LLIST & LPRINT software)

[ ] TRS-80 RS232 Communications Interface (Makes your TRS-80
a full I/O terminal to timesharing systems the world
over. Gives you intelligent or dunb terminal capabilites
at 110 or 300 BAUD. Also includes Printer Interface
above with 20 mA current loop & TTL level 1/0 options.)

- TRS-80 is a trademark of the Tandy Corporation -

§5

5 •

★ E30

INCORPORATED

5071/2 E. McKINLEY HWY. MISHAWAKA, IN 46544
(219) 255-3035

$62.95

* ELECTRONIC SYSTEMS MARKETING

PLUS $1.50
POSTAGE &
HANDLING

iS Reader Service— see page 227

Microcomputing, October 1979 1 07

CLAfflFIEDS

Classified advertisements are intended for use by persons desiring to buy, sell or
trade used computer equipment. No commercial ads are accepted.

Two sizes of ads are available. The $5 box allows up to 5 lines of about 35 charac-
ters per line, including spaces and punctuation. The $10 box allows up to 10 lines.
Minimize use of capital letters to save space. No special layouts allowed. Payment is
required in advance with ad copy. We cannot bill or accept credit.

Advertising text and payment must reach us 60 days in advance of publication
(i.e., copy for March issue, mailed in February, must be here by Jan. 1). The publisher
reserves the right to refuse questionable or inapplicable advertisements. Mail copy
with payment to: Classifieds, Kilobaud Microcomputing, Peterborough NH 03458.
Do not include any other material with your ad as it may be delayed.

Digital Group Z-80 26K system with Cen-
tronics 700 printer, four Phi-deck digital cas-
sette drives, all cabinets, PHIMON moni-
tors, Business Basic. Used 12 months. Best
offer over $4500 plus shipping. Bob Bre-
count, 3301 Morningside, Victoria TX
77901. (512) 575-1257.

H8 Users! Tired of lack of support for your
H8? I have available a set of construction ar-
ticles of various useful things to do with your
H8 via a parallel board: 16 Channel control-
ler, Selectric interface, jogging computer,
DAC, Telephone controllers, etc. For more
info, write Henry Fale, 2918 S. 7th. St., She-
boygan WI 53081. (414) 452-4172.

For Sale for Lease: Intell MDS 220 with dou-
ble density disk drive and ICE 80. Also
PROM programmer and line printer. Con-
tact Gizelle Gil, 3156 Avalon Ct., Palo Alto
CA 94306.

Teletype for Sale: Mite Corp. (Military Ver-
sion) Mod. 30605-2. Similar to Expandor
Inc. Black Box Printer, but with keyboard
and programmable internal/external loop
supply. Excellent cond. with manuals and
6800 routines. First $200 takes it. Call Tom
at (904) 752-8384.

Wanted: Will pay reasonable price for wired
and working E&L’s MMD-1 microproces-
sors. Gerald Malseed, 8102 LaSalle Rd.,
Towson MD 21204. 825-4266. Leave phone
number, will call back.

Heath H8, 8K RAM, Ser I/O, $499. Integral
Data Systems IP-225 printer w/tractor feed,
$799. All equip, mint condx. Steve, K1RF, 4
Fullin Court, Norwalk CT 06851. (203)
846-21 14 eves.

For Sale: Heath Hll computer with HI 1-2
par. int. & 2 HI 1-1 mem cards. Fully assem.
& tested. Asking $1675. Chris Robinson,
1805 Roswell #29M, Marietta GA 30062.
(404) 977-1891.

Synertek SYM-1 for sale or trade for old/
new cameras. Incl. all manuals, 4K RAM,
I/O display, reg. pwr. sup.: $195. Call (516)
921-3603 collect anytime.

For Sale— Alpha-Micro Computer— Includes
AM- 100 16 bit CPU, TEI cabinet & power
supply, 64K RAM, 10MB Control Data
Hawk Disk Drive, AMOS Operating Sys-
tem, Business software (accounts receivable,
general ledger, payroll). C. Hayes 62 South
Franklin St., Wilkes-Barre PA 18773, (717)
823-3101.

Canadians— Technico TMS9900 microcom-
puter with Instant Assem ber, 2K on-board
RAM, RS-232 and TTY interfaces, $375.
Video terminal, 16 by 64, upper- and lower-
case, heavy power supply will run single
board computer. Nice case and keyboard
RS-232, $400. Hitachi video monitor, $200.
Prime 21L02s — 450 ns, $95 for 64. Will also
ship to US. Bill Peters, 194 Oakwood Ave.,
Winnipeg, Manitoba R3B 0N2. (204) 475-
4640 evgs.

Reconfiguring my system. Tarbell cassette
interface, $90; DG PT96 printer + P/S 120
cps, $350; Mits 8-bit PIO (used with PT96),
$50; Portacom terminal + 10 key +
modem, $800; Memorex 1280 terminal,
$1000; 10-120 cps (impact), print belts, spare
parts, documentation, tractor and friction
feed. Offers? Trade? (805) 985-1341.

Digital Group SYS-3 Z-80 system. 18K,
4-drive phi-decks, 9" CRT, Maxi-switch key-
board, all in DG cabinets. Phimon & other
software. Make offer to J. Angell, 510
Davidson, Apt. 3, Chula Vista CA 92010.
(714) 427-7834.

For Sale— MSI 6800 computer with 56K
RAM. 2— MSI 8" floppy disks. Beehive 150
terminal, Centronics 779 printer. Software
Dynamics BASIC Compiler and SDOS.
BASIC 1 .4 and DOS, all programs and man-
uals. Cost $9500, will sell for $6900. Call
Ron (215) 297-5946. PO Box 176, Solebury
PA 18963.

For Sale: SWTP PR-40 Printer. Good Cond.
3 rolls paper. Went to larger unit. First
cashiers check for $150. Firm. Jim Schuster,
2804 Killarney, Cary IL 60013 (312) 639-
0294 Eves.

For Sale: TRS-80, Level 1, 16K complete sys-
tem. Keyboard, video display and cassette
recorder. Also included are games such as:
Invasion Force, Star Pilot, etc. 18 software
programs in all. System only 7 months old.
Voice synthesizer and manual included. All
this only $1211. R. Wiley, 1009 S. Sterling
Ave., Tampa FL 33609.

For Sale: Imsai 8080, 22-slot motherboard
2P + S, Tarbell cassette, 16/32K EPROM,
Godbout active terminator, 8K Seals + 24K
Godbout RAM, H9 terminal, Mullen Exten-
dor, $2000. Larry, 516 E. St., Galt CA
95632. (209) 745-1843.

Tractor-feed 132 column printer— almost
new Centronics 700, with service contract!
Plugs into TRS-80, incl. service manual &
extra ribbons. $1000 or offer. Stand, $85.
(213)997-0882.

Heath H-9 Video Terminal— Excellent con-
dition-Make Offer-(419) 529-5453. Frank
Mowery, 920 Earick Road, Mansfield OH
44903.

Integral Data Systems IP-225 dot matrix
printer with tractor feed, all options and par-
allel interface cable. Can be rewired simply
for serial interface. Never used— in original
shipping carton. Paid $1200. Take $950.
Hitachi P-05 12* TV with Pickles & Trout
TV Mod Kit installed, $85. Call me at (617)
872-3469 or write Dennis Eberl, 153 2nd St.,
#163, Framingham MA 01701.

For Sale: Centronics Micro Printer, RS-232,
electrographic printing, 4.6 * wide; 20, 40, 80
ch/line; w/20 rolls of paper, $350 or offer;
C. Looney, 3406 Notre Dame St., Hyatts-
ville MD 20783.

REVIEWS

(from page 14)

mathematics or electronics, it
leads the reader through binary
states, various number systems,
Boolean algebra and logic charts.

Then comes the fascinating
and useful section: “Manipulat-
ing Logic Expressions. ” If
you’ve ever tried to hook up a
TTL circuit from a magazine, for
example, and wondered if you
could use some NAND gates that
you have instead of the 3-input
NOR gate specified, this could be
a real lifesaver.

My own approach to TTL cir-
cuit “design” has been, “If I
have a one here and a one there,
then there’ll be a zero here. Now,
let’s see, a zero here and a one
here. ...” In a few paragraphs,
this course explains how to work
it all out with just a few simple
but powerful rules.

Electronic logic symbols and
devices are dealt with — not exten-
sively, but enough to show you
how to apply the theory to “real
things,” such as switches and
AND gates.

At several points in the course,
the reader is invited to answer
some “home study questions.”
The questions are the real essence
and beauty of the work; they

show you just how well you’re
doing, and they help to hammer
the information home. My initial
impression was that more exam-
ples and explanations should
have been included, especially in
the application of the DeMorgan
Theorem. But when I missed
some questions and went back to
see why, things fell into place.

There’s an 8-page “table of
equivalent symbols,” which is in-
teresting by itself. It shows, for
example, about a dozen different
ways that AND gates are drawn
by various organizations.

This “mini-course” is well
written and covers a lot of
ground. A word of caution:
Don’t begin by leafing through
the course. I did — and scared my-
self so badly when I saw things
like A( A + B + C+ D + E) = A
that I put the course away for sev-
eral weeks. Take it as it comes
and it will all make sense.

We are told that “logic is the
language of organization.” This
course will help you to get orga-
nized. It may even set you to
thinking of alternative ways to
skin non-computer-related cats.

The “Logic — Home Study
Course” is worth more than its $3
cost. Compliments to author
Aronson and to Measurements &
Control for a fine job.

Dennis G. Brewer
New York NY

CONTEST!

Winner of the “best article” for July is F. R. Ruckdeschel,
author of “1C Logic Tester.”

The Book Nook winner is Larry L. DeRosier of Minneapolis
MN, and winner of a lifetime subscription is J. D. Lawyer of
Dayton OH.

Congratulations, all.

Reader Responsibility

One of your responsibilites, as a reader of Kilobaud MICRO-
COMPUTING, is to aid and abet the increasing of circulation
and advertising, both of which will bring you the same benefit: a
larger and even better magazine. You can help by encouraging
your friends to subscribe to Kilobaud MICROCOMPUTING. Re-
member: Subscriptions are guaranteed— money back if not de-
lighted, so no one can lose. You can also help by tearing out
one of the cards just inside the back cover and circling replies
you’d like to see: catalogs, spec sheets, etc. Advertisers put a
lot of trust in reader requests for information. To make it more
worth your while to send in the card, a drawing will be held each
month and the winner will get a lifetime subscription to
Kilobaud MICROCOMPUTING !

108 Microcomputing, October 1979

Los Angeles CA

Featuring: PolyMorphic, North Star, Imsai,
Cromemco, Extensys, Speechlab products
and Poly-80 Use/s Croup software exchange.
All products 1Cfc20% off list. We won't be
undersold! A-A-A-A Discount Computer
How's, 1477 Barrington, Suite 17, Los Angeles
CA 90025, 477-8478.

Palo Alto CA

Systems available for immediate delivery:
word processing; multiprogramming, multi-
user work in process; business; medical/dental
billing and accounts receivable. Software and
hardware guaranteed Byte of Palo Alto, 2233
El Camino Real, Palo Alto CA 94306, 327-8080.

San Francisco CA

Apple Computer systems, peripherals, soft-
ware and literature. Knowledgeable staff,
after-sales support. Ongoing free BASIC
classes and 'tutorials for system customers.
Educators, businesspersons, new users
welcome. Village Electronics, 5811 Geary
Boulevard, San Francisco CA 94121, 688-4244.

San Leandro CA

From personal computers to small systems:
North Star, Horizon, DD, Sorcerer, Godbout,
TRS-80, Imsai, Verbatim, terminals, printers,
floppies, boards, software, books, magazines.
Custom programming. Computer Store of San
Leandro, 701 MacArthur Blvd., San Leandro
CA 94577, 569-4174.

Torrance CA

If you're serious, come see us! Complete sys-
tems for business, special and personal appli-
cations. Packaged and proprietary software.
Custom programming. Quality: Apple II,
Exidy, Alpha Micro and CP/M systems. Serv-
ing southern California better. Omega Micro
Computers, 3447 Torrance Blvd., Torrance CA
90503, 370-9456.

Denver CO

Experimenters' Paradise. Electronic and
mechanical components. Computer People,
Audio People, Hams, Robot Builders, Experi-
menters. Open six days a week. Gateway Elec-
tronics Corp., 2839 W. 44th Ave., Denver CO
80211, 458-5444.

Stamford CT

The Computer Place in downtown Stamford
features Apple, North Star. DEC and others.
Specializing in small business applications.
We are a DEC OEM and supply integrated
business systems with word processing.
Books, magazines, peripherals and good ad-
vice. The Computer Place, 21 Atlantic St.,
Stamford CT 06901, 356-1920.

Shop the store nearest you

Washington DC/Northern VA

Authorized Dealer: Processor Technology,
Corp.; PET; Sorcerer; KIM. Word processing,
data-base management, general accounting
software. Books & magazines. Parts & acces-
sories. Complete service center. Tyson's Com-
puter Emporium, 1984 Chain Bridge Rd.,
McLean, VA 22101, 821-8333; and George-
town Computer Emporium, 3286 M St., NW,
Washington DC 20007, 337-£545.

Pompano Beach FL

Business systems, personal systems, whatever
the application, we can help. Consulting, pro-
gramming, education and maintenance. Ser-
vice, support and professionalism at afford-
able prices. Computer Age Inc., 1308 N. Fed-
eral Hwy., Pompano Beach FL 33062, 946-
4999.

Venice FL

Discount prices & professional service: Cro-
memco, Northstar, Vector Graphic, DEC, Tl,
Thinker Toys, Intertube, Soroc, Centronics,
NEC, Selectric interfaces, Microdasys. Com-
plete business & medical billing software
available. MicroAge & Serendipity software
discounted. Sara-Tech Electronics, Inc., Com-
puter Division, PO Box 692, Venice FL 33595,
485-3559.

Arlington Hts. IL

Lowest prices, never undersold, postpaid in
USA — Teletype 43 keyboard printers — Mid-
west Scientific Instruments Computers —
SS-50 bus peripherals — open 6-11 PM daily.

Data Mart, 914 East Waverly Drive, Arlington
Heights IL 60004, 398-8525.

Aurora IL

Personal and small business microcomputer
systems, peripherals, software, books and
magazines. Apple, North Star, Cromemco sys-
tems. Weekdays 12-8, Saturdays 10-5. Farns-
worth Computer Center, 1891 N. Farnsworth
Ave., Aurora IL 60505, 851-3888.

Chicago IL

Computer Hardware/Software Specialists for
home and business. Largest selection of com-
puter books, magazines and copyrighted soft-
ware in Chicago Metro area. Experienced fac-
tory-trained service department. Feature Ap-
ple and Alpha Microsystems and accessories.
Data Domain of Schaumburg, 1612 E. Algon-
quin Road., Schaumburg IL 60195, 397-8700.

Naperville IL

Computer systems design, programming and
consultation by computer experts. Dealer for
SSM, Integrand, Tarbell, Ithaca Audio, Verba-
tim, Diablo and others. Discount prices on
many items. Wilcox Enterprises, 25W178-39th
St., Naperville IL 60540, 420-8601.

Laurel MD

Exidy Sorcerer & accessories, Vista floppy-
disk systems, memory boards, software &
books, full line of ham & SWL equipment. The

Comm Center, Laurel Plaza, Rte. 198, Laurel
MD 20810, 792-0600.

Worcester MA

Computer products for personal and business
systems. Stocking full line of Instant Soft-
ware, G2 and Personal Software for TRS-80,
Apple, PET, Sorcerer. Open six days. Comput-
er Packages Unlimited, Centerwood Terrace,
244 West Boylston St., West Boylston MA
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Complete systems for business, professional
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48135, 422-2570.

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Full-line microcomputer store. Ohio Scien-
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Ohio Scientific Authorized Dealer. Complete
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Store hours: Mon-Sat 9-5. Custom software
design and programming. To take advantage
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call, write or visit: Frisch Computer Systems,
Inc., 1415 Arcade St., St. Paul MN 55106,
771-7569.

St. Louis MO

Brooklyn NY

Specialists in analyzing business needs; con-
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Micronomics Business Systems, Inc., 1061
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Complete line of business computer hard-
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Ohio Scientific Authorized Dealer. Comput-
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Processor Technology, North Star HORIZON,
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of books, components and peripherals;
classes in our Seminar Room The Computer
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We've got it all. Business systems. Personal
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York PA

SS-50 Buss Stop. Business & personal systems:
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Les meilleurs produits S-100 a des prix sans
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Dealers: Listings are $15 per month in prepaid quarterly payments, or one yearly payment of
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MAILROOM PLUS 6

Make Your TRS 80 Work Like A Mini-IBM!

Mailroom Plus was developed for the National Rifle Association membership mailings. It
features sorting by last name or member number in addition to zip code. The program will sort
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search all records for category, name, state, zip (or any other search code) and print these
records on labels or in tabular form. It separates large Files into smaller ones by state or zip or
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THE PERIPHERAL PEOPLE ^P52

PO Box 524, Mercer Island, WA 98040

VISA ’

Master Charge and VISA cards welcomed

Reader Service— see page 227

Microcomputing, October 1979 109

Richard Price
5812 W. Giddings
Chicago IL 60630

Arena

Be kind to your lionesque computer, and you might later be spared in the “arena.'

F ranz hefted his two-handed
sword and strode without
hesitation to the center of the
arena. His keen eyes barely had
time to register the frenzied,
screaming blur that suddenly
bore down upon him. Blood
gushed from Franz’s arm as he
hastily parried the rain of blows
from his wild-eyed opponent.
Could the berserker possibly
keep up this furious pace?

No! ... the wild man paused
—it was less than a second, but
time enough for a battle-sea-
soned warrior to strike with a

stunning force. Franz wasted
no pity on his fallen foe. His
next blow opened a mortal
wound. Panting, sweating,
bleeding, the gladiator raised
his clenched fist skyward in the
ageless sign of victory . . . and
read, “DO YOU WANT TO PLAY
AGAIN?”

Arena is a game of mortal
combat for two to five players.
It was written using Southwest
8K BASIC on a 6800 Gimix
Ghost system. The winner of
each game is the last person
still alive -combat is always

123456789012345* FRANZ’S TURN

F B

123456789012345

YOUR CONDITION IS GOOD (100)

YOU ARE ATTACKING BORIS
YOU ARE ENGAGED BY BORIS

FACING:

432432

\l/ \l/

5-F***-B-1

/l\ /l\

678678

“to the death.” Each player
must use strategy and be ready
to take advantage of the oppor-
tunities chance provides.

Instructions

The Turn. Arena proceeds as
a series of turns during which
each player is allowed one
move. The order of moves with-
in a turn is not fixed and may be
influenced by various factors,
such as movement and combat
on previous turns.

The Move. A player’s move
consists of the following se-
quence of events:

1. The player is asked by
name to press the return key.
This is intended to give him
time to chase other players
away from the screen so that
they don’t see his status
display.

2. The playing field, the play-
er’s status and the facing ro-
settes are displayed.

3. The player is asked to
choose an option from the list
presented.

4. The player is allowed to
adjust his combat attention
percentage.

5. If the attack option was
chosen, combat is resolved.

The Display. At the start of a
player’s move, the screen is
filled with a display (see Fig. 1).
The left side of this display is
the playing field. The right side
gives the player’s status and a
graphic indication of the direc-
tion in which each player is fac-
ing.

These facing indicators, or
rosettes, contain the first letter
of a player’s name surrounded
by the numbers from one to
eight. These numbers are used
to refer to the eight directions
in which a player may be facing.
An asterisk overlays the num-
ber that indicates a given
player’s current direction. The
first letter of a player’s name is

Fig. 1. Arena display.

Fig. 2. Program flowchart.

110 Microcomputing, October 1979

also used to indicate the play-
er’s position on the playing
field.

this movement would not di-
minish the player’s number of
energy units. Energy units can

damage, which permanently
lowers the hit player’s energy
units by an amount that may

strategy, but simple enough to
be easily learned. The system
includes 24K of memory and a

Player Status. The player’s
status consists of his condition
expressed in energy units.
Each player starts with 100
units. The name of the oppo-
nent under attack by the player
(If any) and a list of any oppo-
nents attacking (engaging) the
player are printed below the
status line. Notice is also given
here of a stunned condition.

Options. The options avail-
able to the player on a given
turn depend on his status. Pos-
sible options are MOVE, TURN,
DISENGAGE, ATTACK and
STAND. The first three options
require that the player’s energy
units be sufficient to cover the
energy costs, but they do not
affect the player’s status.
MOVE costs 15 units per square
(X + Y), and a maximum of four
squares may be moved. TURN
costs five units per facing num-
ber. DISENGAGE costs 15 units
and may or may not be suc-
cessful. STAND is a “do
nothing” option. ATTACK leads
to combat.

To attack an opponent, the
player must be adjacent to and
facing the opponent. For exam-
ple, a player who wished to
move up one space and left two
spaces would require 45 energy
units. If he also wished to turn
90 degrees, a total of 55 energy
units would be required. But

only be expended in battle.

Combat Attention. The heart
of combat strategy in Arena is
the combat-attention percent-
age. This percentage enables
the player to divide his atten-
tion between attack and de-
fense. For example, a player
whose combat attention is 100
percent on attack and 0 percent
on defense (a berserker) will be
a formidable opponent when at-
tacking, but won’t bother much
with defense.

Combat. If the player chooses
the ATTACK option, his move
ends with combat. The results
of combat take effect immedi-
ately. If the attacker misses or
is parried, the defender gets a
return swing. A hit results in

2000

Fig. 3. Turn subroutine flow-
chart.

4000

Fig. 4. Move subroutine flowchart.

vary from 1 to 50 units, depend-
ing on the severity of the blow.
This is the only way that energy
units may be lost.

System Requirements

When I first acquired my
Gimix computer, I decided to
explore its capabilities by writ-
ing a game program. Having
worked with computers for over
ten years, I decided my initial
game effort would be fairly
complex in design. I also decid-
ed to apply the same design
techniques that I would use in a
business-programming envi-
ronment.

The rules of Arena are com-
plex enough to allow for real

Gimix video board; the program
uses less than 20K.

Arena uses character graph-
ics to display a 15x11 playing
field and a “facing rosette” for
each player. To solve the prob-
lem of BASIC’s almost nonexis-
tent output formatting, I used
POKEs to place the players on
the field and the directional
markers in the rosettes (see
POKE PLAYERS subroutine,
lines 5900 to 5950). This tech-
nique requires some form of
memory-mapped display.

Constant B is set to the start
of my video board’s display
memory. It should be fairly easy
to modify the POKE PLAYERS
subroutine to work with a video

Program listing.

0100 REM *** ARENA - BY RICHARD PRICE #**

0110 REM ***

0200 REM BANNER

0210 PRINT CHR$ < 12) ? * ARENA VERSION 2.0'

0220 PRINT

0230 PRINT ' A GAME OF MORTAL COMBAT FOR 2 TO 5 PLAYERS*

0240 PRINT

0260 PRINT

0500 REM CONSTANTS

0510 E=100 ♦ 01 = 15 J C2=5J C3=15

0520 X1=15:Y1=11

0530 B=61440

0540 M=5

0550 LINE= 0

0560 DIM T(8)

0565 DATA 132, 4 , 2,0, 128 r 256 , 258, 260
0570 FOR 1=1 TO 8J READ T(I>: NEXT I
0575 DIM U<3,3)

0580 DATA 4 , 5 , 6 , 3, Or 7, 2, 1 , 8

0585 FOR 1=1 TO 3J FOR 11=1 TO READ U<I,I1)J NEXT II J NEXT I

0700 REM FUNCTIONS

0710 DEF FNA ( X ) =6# ( X-- 1 ) + 1

0800 REM ARRAYS

0810 DIM L(M) , LI ( M )

0820 DIM S<M) ,S1(M> ,S2<M>

0830 DIM X(M),Y(M),F(M)

0840 DIM J(M)

1000 REM ARENA PROGRAM

1001 GOSUB 1500
1100 REM MAIN LOOP
1110 GOSUB 2000
1120 GOSUB 9300

1130 IF Z>1 THEN 1100 J REM TWO OR MORE ALIVE

1150 GOSUB 2500

1170 PRINT 'PLAY AGAIN * i

1180 GOSUB 9000

1190 ON 19 GOTO 1000,1200

1200 END

1500 REM INITIALIZE SUBROUTINE
1505 N$="JREM CLEAR NAMES

1510 PRINT 'ENTER NUMBER OF PLAYERS ( 2 TO '?MJ')'?

1520 INPUT N
1530 N=INT <N>

1540 IF N>M THEN 1500
1550 IF N<2 THEN 1500
1570 GOSUB 1800
1600 FOR 1=1 TO N
1610 S < I )=2
1620 SKI )=0»S2( I )=0
1630 L(I)=E: LI ( I ) =E/2
1640 J(I)=0
1650 GOSUB 1700
1660 NEXT I

1670 ON N GOSUB 3000,3100,3200,3400,3600,3800
1690 RETURN

1700 REM NAME ENTRY PROCESSOR

1710 PRINT 'PLAYER ' 5 1 f " - ENTER YOUR NAME (1 TO 6 CHARS ) ' i

1720 INPUT A$JIF LEN(A$>=0 THEN 1700

1730 IF LEN(A$)>6 THEN 1700

1735 GOSUB 1900J IF 19=1 THEN 1770

1740 A$=A*+' ' JA$=LEFT$(A$,6)

1750 N$=N$+A$

1760 RETURN

1770 REM ENTRY POINT

1780 PRINT 'EACH NAME MUST START WITH A UNIQUE FIRST CHARACTER'
1790 GOTO 1700
1800 REM RANDOMIZE

1810 INPUT 'ENTER A SIX DIGIT NUMBER', 19
1820 I9=RND< 19)

1830 RETURN

1900 REM NAME CHECK

Microcomputing, October 1979 111

1905

19=0

4810

1910

IF 1=1 THEN RETURN

4820

1920

FOR 13=1 TO I

4900

1930

IF LEFT$(A*f1)=MID*(N*f

6*(I3-l)+lrl> THEN

LET

19=1

4910

1940

NEXT 13 J RETURN

4920

2000

REM TURN SBROUTINE

4960

2010

GOSUB 2100

5000

2020

FOR 14=1 TO N

5010

2030

GOSUB 2300

5020

2040

GOSUB 4000

5030

2050

NEXT 14

5040

2060

RETURN

5050

2100

REM ORDER PLAYERS FOR THIS TURN

5100

2110

FOR 1=1 TO N

5105

2120

SI ( I )=RND+1-S2< I )

5110

2130

S2 ( I ) =0

5120

2140

NEXT I

5130

2150

RETURN

5140

2300

REM SELECT THE NEXT PLAYER TO MOVE

5150

2310

1 = 1

5160

2320

FOR 12=1 TO N

5170

2330

IF SI ( I2)>S1 ( I ) THEN LET 1=12

5200

2340

NEXT 12

5210

2345

S1(I)=0

5220

2350

RETURN

5230

2500

REM FINALIZE SUBROUTINE

5240

2510

RETURN

5250

3000

REM POSITION 1 PLAYER

5260

3010

X<1)=1

5270

3020

Y< 1 )=( Yl+1 )/2

5300

3030

F(l)-1

5310

3050

RETURN

5315

3100

REM POSITION 2 PLAYERS

5320

3110

X<2)=X1

5330

3120

Y(2)=(Yl+l)/2

5335

3130

F<2)=5

5340

3140

GOSUB 3000

5350

3150

RETURN

5400

3200

REM POSITION 3 PLAYERS

5410

3210

X(l)=l

5420

3220

Y(l)=<Yl+l>/2

5430

3230

F< 1 )=1

5500

3240

S2< 1 )=1

5510

3260

X<2)=INT<3*<Xl+l)/4)

5520

3270

Y(2)=l

5530

3280

F(2)=7

5600

3310

X<3)=X(2)

5610

3320

Y<3)=Y1

5620

3330

F<3)=3

5630

3350

RETURN

5700

3400

REM POSITION 4 PLAYERS

5710

3410

GOSUB 3100

5720

3420

X<3)=(Xl+l)/2

5730

3430

Y(3)=l

5800

3440

F(3)=7

5810

3460

X<4)=X(3)

5820

3470

Y< 4 ) =Y1

5830

3480

F< 4 ) =3

5900

3490

RETURN

5910

3600

REM POSITION 5 PLAYERS

5920

3610

GOSUB 3400

5930

3620

X(5)=(X1+1 )/2

5935

3630

Y<5)=( Yl+1 )/2

5940

3640

F<5)=INT(8*RND+1)

5950

3660

S2(5)=-l

6000

3670

RETURN

6010

4000

REM MOVE SUBROUTINE

6020

4010

IF S(I>=0 THEN RETURN

6030

4120

M1=L ( I )

6040

4125

M4=0

6050

4130

IF S(IX>1 THEN 4200

6100

4140

Ml=Ml/2 J J(I)=0

6110

4200

FOR 13=1 TO N

6120

4210

IF J( 13) = 1 THEN LET M4=!

M4 + 1

6130

4220

NEXT 13

6140

4230

GOSUB 4500

6150

4235

M2=J< I )

6155

4240

J(I)=0

6160

4310

GOSUB 6000

6170

4320

GOSUB 4400

6200

4330

S( I )=2

6205

4340

IF J(I)=0 THEN RETURN

6207

4360

GOSUB 8000

6210

4370

RETURN

6215

4400

REM ATTACK V. ADJUSTER

6220

4410

PRINT * YOUR ATTENTION IS **L1<I)**% ON ATTACK

AND **

6230

4420

PRINT 100-L1 <!>**% ON DEFENSE. OK**

6240

4430

GOSUB 9000

6245

4440

IF 19=1 THEN RETURN

6250

4450

INPUT ’ENTER NEW ATTACK

%*fL1(I>

6260

4460

L1(I)=INT(L1(I))

6270

4470

IF LKIXO THEN 4450

6280

4480

IF L1(I)>100 THEN 4450

6290

4490

RETURN

6300

4500

REM DISPLAY PROCESSOR

6310

4505

PRINT CHR* < 12) *

6320

4510

PRINT MID*(N*f6*<I-1)+1

» 6 ) * * HIT RETURN. *i

6400

4520

INPUT A$

6405

4525

PRINT CHR*( 12) r

6407

4530

GOSUB 4600 J GOSUB 4900

6408

4535

13=1 J GOSUB 4700 J PRINT

6410

4540

13=2 J GOSUB 4800 J GOSUB

5000

6420

4545

13=3 J GOSUB 4700 J PRINT

6430

4550

13=4 J GOSUB 4800 J GOSUB

5100

6440

4555

13=5 J GOSUB 4700 J GOSUB

5200

6450

4560

13=6 J GOSUB 4800 J GOSUB

5300

6460

4565

13=7 J GOSUB 4700 J PRINT

TAB < 36) * ’FACING J *

6465

4570

13=8 J GOSUB 4800 J GOSUB

5400

6470

4575

13=9 J GOSUB 4700 J GOSUB

5500

6500

4580

13=0 J GOSUB 4800 J GOSUB

5600

6510

4585

13=1 J GOSUB 4700 J GOSUB

5700

6520

4590

GOSUB 4600 J GOSUB 5800

6525

4595

GOSUB 5900 J RETURN

6530

4600

REM DSPLY MAP EDGE

6540

4610

PRINT ** 123456789012345 **i

6550

4620

RETURN

6600

4700

REM DSPLY ODD MAP LINE

6610

4710

PRINT 13* *

" 1

113*

6613

4720

RETURN

6615

4800

REM DSPLY EVEN MAP LINE

6617

PRINT 13* * '»I3?

RETURN

REM DSF’LY NAME
PRINT TAB < 36) *

PRINT MID*(N*fFNA(I> t6 ) * * 'S TURN - ■

RETURN

REM DSPLY CONDITION

PRINT TAB(36> * ‘YOUR CONDITION IS **

IF L( I )>=80 THEN PRINT ■ GOOD ( 1 ? STR$ (Ld))}’)*! RETURN

IF L< I >>=60 THEN PRINT ’FAIR ( * * STR$ < L < I ) ) * * ) * J RETURN

IF L(I)>=40 THEN PRINT * POOR ( ■ * STR$(L( I) ) * * ) " JRETURN

PRINT "BAD <* *STR*(L<I) ) * *>* JRETURN

REM DSPLY ATTACKING

IF S<I)=1 THEN 5150

IF J(I>=0 THEN PRINT J RETURN

PRINT TAB< 36) * • YOU ARE ATTACKING **

PRINT MID*<N*f6*< J(I)-1>+1f6)

RETURN
REM ENTRY

PRINT TAB(36)**Y0U ARE STUNNED*

RETURN

REM DSPLY ENGAGED 1

IF M4=0 THEN PRINT JRETURN

PRINT TAB<36) * *YOU ARE ENGAGED BY '*

16=0 JREM THIS VALUE USED IN SUBROUTINE 5300
GOSUB 9100

PRINT MID$(N$f6*<I6-1)+1f6)J
IF M4>2 THEN PRINT *f**

PRINT JRETURN
REM DSPLY ENGAGED 2
IF M4<2 THEN PRINTJRETURN
PRINT TAB(36> *

IF M4>3 THEN GOSUB 9100 JPRINT MID$<N*r6#< 16-1 >+l f6) *
IF M4>2 THEN GOSUB 9100 JPRINT MID$<N*f 6*< 16-1 >+l f6) *

GOSUB 9100

PRINT 'AND * SMID$<N$f6*<I6-1)+1f6>

RETURN

REM DSPLY FACING 1
A*= * 4 3 2*

GOSUB 9200
RETURN

REM DSPLY FACING 2
A$= * \ ! / *

GOSUB 9200
RETURN

REM DSPLY FACING 3
A$= * 5- -1*

GOSUB 9200
RETURN

REM DSPLY FACING 4
A*= ' / ! \ *

GOSUB 9200
RETURN

REM DSPLY FACING 5
A*=* 6 7 8*

GOSUB 9200
RETURN

REM POKE PLAYER ONTO SCREEN
FOR 13=1 TO N

POKE < B+64*Y<I3)+2*X(I3) fASC< MID* <N$f6*< 13-1) +1f1> ) )
POKE < B+671+6*I3fASC<MID*<N*f6*(I3-1) + 1f1> ))

POKE< B+541+T(F(I3))+6#I3f42)

NEXT 13
RETURN

REM OPTIONS PRICESSOR
PRINT 'YOUR OPTIONS ARE **

IF S(IX>1 THEN PRINT ’ATTACK, *?

IF M4=0 THEN PRINT *MOVEf **

IF M4O0 THEN PRINT *DISENGAGEf * *

PRINT 'TURN OR STAND. CHOOSE ONE**

INPUT A*

IF LEFT*(A*f1)=*A* THEN GOTO 6200
IF LEFT* < A$f1) = *D* THEN GOTO 7000
IF LEFT*< A*f 1 )=*M* THEN GOTO 6400
IF LEFT*(A*f1)=*T* THEN GOTO 6700
IF LEFT$<A$f1)=*S* THEN GOTO 6900
REM ENTRY POINT
PRINT * WHAT* f
GOTO 6100
REM ATTACK

IF S<I)=1 THEN PRINT *WHAT**J GOTO 6100
IF M2<>0 THEN J( I ) =M2 J RETURN
INPUT 'ATTACK WHO*fA$

13=0

FOR 12=1 TO N

IF LEFT*(A*f1>=MID*<N*f6*<I2-1)+1f1) THEN LET 13=12

NEXT 12

IF 13=0 THEN 6200

IF 1 = 13 THEN PRINT 'YOU CAN'T ATTACK YOURSELF. * ? J GOT06000
M5=X< I3)-X< I ) * M6=Y <I3)-Y(I)J GOSUB 9400
IF M7<>0 THEN 6300

PRINT * YOU MUST BE NEXT TO THE PERSON YOU ATTACK.*

GOTO 6000

IF F( I ) =M7 THEN LET J(I)=I3J RETURN

PRINT * YOU MUST BE FACING THE PERSON YOU ATTACK.*

GOTO 6000

REM MOVEMENT

IF M4<>0 THEN 6155

PRINT * YOUR CURRENT POSITION IS **

PRINT STR$ <X(I))f*f** STR* ( Y < I ) ) f

INPUT *. ENTER NEW POSITION* fM5fM6

GOSUB 6600

IF M7=0 THEN 6500

PRINT * YOUR NEW POSITION IS **

IF M7*l THEN PRINT *OUT OF RANGE. **

IF M7=2 THEN PRINT 'OCCUPIED. **

IF M7=3 THEN PRINT ‘OUT OF BOUNDS. **

PRINT * TRY AGAIN. *J GOTO 6000
I9=C1*(ABS(M5-X(I))+ABS(M6-Y(I)))

IF I9>M1 THEN PRINT *N0 ENOUGH ENERGY. **J GOTO 6000

X< I )=M5 J Y< I ) =M6 J M1=M1-I9

S2(I)=.3

PRINT * YOUR FACING IS **F<I)**. OK**

GOSUB 9000J IF 19-1 THEN RETURN

GOSUB 6700 J RETURN

REM MOVE CHECK

M7=0 J M5=INT (M5) J M6=INT(M6)

IF M5<1 THEN 6670
IF M5>X1 THEN 6670
IF M6<1 THEN 6670

112 Microcomputing, October 1979

WANT A CLASSY CHASSIS?

SYSTEM 68 by GIMIX

The Ultimate in SS 50 BUS Reliability

• A.C. fuse holder

• Removable A.C. cord

• Exhaust fan

• Punched for 16 D type date connectors,
4 video connectors and slotted for
ribbon cables.

• Ventilation slots, direct cooling air over
boards first.

Mainframe: includes chassis
power supply switches,
fan and mother board $748-19

16K Systems from $1294.29
Includes: Mainframe cabinet,
mother board, power supply,
fan, CPU, 16K static RAM, and
choice of I/O card.

» Holds 2 5V4 disk drives (not included)
» GIMIX disk regulator cards (optional)
mount on drives and wire to filter
assembly board
» LED power indicator
► 3 position removable keyswitch
(Off; Power On-Reset Off; Both On)

• Reset - can be locked out

CABINET

• Optional filler plates (when no drives
are used)

Heavyweight aluminum painted inside and out in grey and
black baked enamel finish. Size: 18” widex21” deepx7” high.

MOTHER BOARD

Hardware reconfigurable to give you the utmost versatility for use with
various SS 50 bus software packages. Gold plated pins to insure long
lasting electrical contact for protection against corrosion. Fifteen 50
pin slots plus eight DIP-switch addressable 30 pin I/O slots con-
figurable to 4 or 8 decoded addresses. The fully buffered I/O block is
addressable by DIP-switch to any 32 or 64 byte boundary and can also
be disabled. UD1 and UD2 of the 50 pin bus can be strapped to UD3
and UD4 of the 30 pin bus. A fully shielded, (.090” thick), double sided
P.C. board with noise reducing ground lines on the bottom side that
separate all data, address, and signal lines, and a full ground plane on
the top side. A 14 position clamping terminal block for all power and
other external connections eliminates soldering, crimping or forming
of wires.

POWER SUPPLY

Designed to power a fully loaded system plus two 5 Vi” disk drives
-and keep running at constant voltage outputs even under adverse A.C.
power input conditions. It consists of: A 550 VA Ferro-resonant cons-
tant voltage transformer, over 16 pounds of brute force custom design-
ed for GIMIX to GIMIX’ specs, an A.C. resonant capacitor, 3 D.C. filter
capacitors, and GIMIX’ unique filter assembly board that sits on top of
the filter capacitors and includes individual fuses for each output,
bleeder resistors, and a clamping terminal block for easy wiring con-
nections. Almost a Quarter-farad of D.C. Filtering. Brown-out and over-
voltage insurance: Supplies 8V at 25 Amps, + 15 Volts at 5 Amps and
- 15 Volts at 5 Amps from A.C. input voltages ranging from 90 to 140
Volts.

SS 50 BUS 80 X 24 VIDEO BOARD

Deluxe

Version

$458.76

Other Video Boards from $198.71

16K SYSTEMS $1294.29

Includes: Mainframe cabinet, mother
board, power supply, fan, CPU, 16K static
RAM, and choice of 1/0 card.

Other packages available.

Add $10. handling charge on orders under $200.

cimix

1337 WEST 37th PLACE ^ G2a
CHICAGO, ILLINOIS 60609
(312) 927-5510 • TWX 910-221-4055

The Company that delivers.

Quality Electronic products since 1975.

»xN15

Featuring

Of* ML 1802

n COSMAC CPU

Own a powerful home computer system, starting for just $99.95 -a price that
gets you up and running the very first night . with your own TV for a video
display. $99.95 ELF II includes RCA 1802 8 bit microprocessor addressable to 64k
bytes with DMA. interrupt, 16 registers, ALU, 256 byte RAM. full hex keyboard,
two digit hex output display, stable crystal clock for timing purposes, RCA 1861
video 1C to display your programs on any video monitor or TV screen and 5 slot
plug in expansion bus Hess connectors) to expand ELF II into a giant!

ELF II Explodes Into A Giant!

Master ELF Il's $99.95 capabilities, then expand with GIANT BOARD
KLUGE BOARD 4k RAM BOARDS ..TINY BASIC ASCII KEYBOARD
LIGHT PEN ELF BUG MONITOR COLOR GRAPHICS 6 MUSIC SYSTEM
TEXT E0IT0R ASSEMBLER DISASSEMBLER VIDEO DISPLAY BOARD
and, another great reason for getting your ELF now-

BREAKTHROUGH!

Netronics proudly announced the release of
the first 1802 FULL BASIC, written by L.
Sandlin, with a hardware floating point RPN
math package (requires 8k RAM plus ASCII and
video display boards), $79.95 plus $2 p&h. Also
available for RCA VIP and other 1802 systems
(send for details)!

Master This Computer In A Flash!

Regardless of how minimal your computer background is now, you can learn
to program an ELF II in almost no time at all. Our Short Course On Micropro-
cessor b Computer Programming- written in non technical language-guides you
through each of the RCA COSMAC 1802's capabilities, so you'll understand
everything ELF II can do and how to get ELF II to do it! Don't worry if you've
been stumped by computer books before. The Short Course represents a major
advance in literary clarity in the computer field. You don't have to be a computer
engineer in order to understand it. Keyed to ELF II, it’s loaded with "hands on"
illustrations. When you're finished with the Short Course, neither ELF II nor the
RCA 1802 will hold any mysteries for you.

In fact, not only will you now be able to use a personal computer creatively,
you'll also be able to read magazines such as BYTE . INTERFACE AGE POPU
LAR ELECTRONICS and PERSONAL COMPUTING and fully understand the
articles. And, you'll understand Iiqw to expand ELF II to give you the exact
capabilities you need!

If you work with large computers. ELF II and the Short Course will help you
understand what they're doing.

Get Started For Just $99.95, Complete!

$99.95 ELF II includes all the hardware and software you need to start writing
and running programs at home, displaying video graphics on your TV screen and
designing circuits using a microprocessor -the very first night-even if you've
never used a computer before.

ELF II connects directly to the video input of your TV set. without any addi
tional hardware, Or, with an $8.95 RF modulator (see coupon below), you can
connect ELF II to your TV's antenna terminals instead.

ELF II has been designed to play all the video games you want, including a
fascinating new target/missile gun game that was developed specifically for ELF
II. But games are only the icing on the cake. The real value of ELF II is that it
gives you a chance to write machine language programs-and machine language
is the fundamental language of all computers. Of course, machine language is
only a starting point. You can also program ELF II with assembly language and
tiny BASIC. But ELF It's machine language capability gives you a chance to
develop a working knowledge of computers that you can’t get from running only

Write and run programs- the
very first night-even if you’ve
never used a computer before!

You’re up and running with video graphics for just $99.95 —
then use low cost add-ons to create your own personal system
that rivals home computers sold for 5-times ELF Il’s low price!

pre recorded tape cassettes.

ELF II Gives You The Power To Make Things Happen!

Expanded, ELF II can give you more power to make things happen in the real
world than heavily advertised home computers that sell for a lot more money.
Thanks to an ongoing committment to develop the RCA 1802 for home computer
use, the ELF II products-being introduced by Netronics-keep you right on the
outer fringe of today s small computer technology. It's a perfect computer for
engineering, business, industrial, scientific and personal applications.

Plug in the GIANT BOARD to record and play back programs, edit and
debug programs, communicate with remote devices and make things happen in
the outside world. Add Kluge (prototyping) Board and you can use ELF II to
solve special problems such as operating a complex alarm system or controlling
a printing press. Add 4k RAM Boards to write longer programs, store more
information and solve more sophisticated problems.

ELF II add ons already include the ELF II Light Pen and the amazing ELF BUG
Monitor-two extremely recent breakthroughs that have not yet been duplicated
by any other manufacturer.

The ELF-BUG Monitor lets you debug programs with lightening speed because
the key to debugging is to know what's inside the registers of the microproces-
sor. And, with the ELF BUG Monitor, instead of single stepping through your
programs, you can now display the entire contents of the registers on your TV
screen. You find out immediately what's going on and can make any necessary
changes.

The incredible ELF II Light Pen lets you write or draw anything you want on a
TV screen with just a wave of the "magic wand." Netronics has also introduced
the ELF II Color Graphics b Music System-more breakthroughs that ELF II
owners w the the first to enjoy!

ELF II Tiny BASIC

Ultimately, ELF II understands only machine language-the fundamental coding
required by all computers. But, to simplify your relationship with ELF II. we've
introduced an ELF II Tiny BASIC that makes communicating with ELF II a
breeze.

Now Available! Text Editor, Assembler,

Disassembler And A New Video Display Board!

The Text Editor gives you word processing ability and the ability to edit
programs or text while it is displayed on your video monitor. Lines and charac
ters may be quickly inserted, deleted er changed. Add a printer and ELF II can
type letters for you -error free -plus print names and addresses from your
mailing list!

ELF It s Assembler translates assembly language programs into hexidecimal
machine code for ELF II use. The Assembler features mnemonic abbreviations
rather than numerics so that the instructions on your programs are easier to
read-this is a big help in catching errors.

ELF ll s Disassembler takes machine code programs and produces assembly
language source listings. This helps you understand the programs you are
working with, and improve them when required.

The new ELF II Video Display Board lets you generate a sharp, professional
32 or 64 character by 16 line upper and lower case display on your TV screen or
video monitor-dramatically improving your unexpanded $99.95 ELF II. When you
get into longer programs, the Video Display Board is a real blessing!

Now Available!

□ A-D/D-A Board Kit includes I channel (expandable to

4) D-A, A-D converters, $39.95 plus $2 postage & hand-
ling. .

□ PILOT Language— A new text-oriented language that
allows you to write educational programs on ELF II with
speed and ease! Write programs for games. . unscram-
bling sentences. . .spelling drills. . .“fill in the missing
word” tests, etc.! PILOT is a must for any ELF II owner
with children. PILOT Language on cassette tape, only
$19.95 postpaid!

□ Game Package on cassette tape (requires 4k RAM),
$9.95 plus $2 postage & handling.

- Clip Here and Attach to Your Order Below!

Netronics R&D Ltd., Dept RE 10
333 Litchfield Road, New Milford, CT 06776
Yes! I want my own computer! Please rush me—

□ RCA COSMAC ELF II language, it's a learning breakthrough lor engineers and laymen
_ kit at S99 95 plus $3 postage and alike $5 postpaid

^ handling (requires 6 3 lo 8 volt AC power q oehucg Metal Cabinet with plexiglas dust cover lor ELF II.

Supp, *» $29 95 plus $2 50 p&h

U Power Supply (required) $4 95 postpaid □ i a m also enclosing payment (including postage & handling) tor

□ RCA 1802 User s Manual $5 postpaid the items checked below 1

D Tom Pittman s Short Course On Microprocessor & Computer □ I want my ELF II wired and tested with power supply. RCA

Programming teaches you |ust about everything there is lo know 1802 User's Manual and Short Course— all tor just $149.95 plus

about ELF II or any RCA 1802 computer Written in nontechnical S3 p&h

ALSO AVAILABLE FOR ELF II

PHONE ORDERS ACCEPTED!
Call (203) 354-9375

Total Enclosed S

(Conn res add tax)

CHARGE IT! Exp Date

□ Visa □ Master Charge

(Bank# )

Account #

I u GIANT BOARD™ kit with cassette I/O RS 232

I C/ TTY I/O. 8- bit P I/O. decoders lor 14 separale I/O
msiruclions and a system momtor/edilor $39 95 plus

$2 p&h

I D Kluge (Prototype) Board accepts up to 36 IC s
$17 00 plus Si p&h

i □ 4k Static RAM kit. Addressable to any 4k page to
I 64k $89 95 p'us $3 p&h

I D Gold plated 86-pin connectors (one required lor each
plug in board) $5 70ea postpaid
□ Expansion Power Supply | required when adding 4k
I RAM) $34 95 plus S? p&h

| □ Professional ASCII Keyboard kit with 128 ASCII
, upper /lower case set 96 printable characters onboard
I regulator parity logic selection and choice ot 4 hand
I shaking signals lo male with almost any computer
I $64 95 plus $2 p&h

| n Deluxe metal cabinet for ASCII Keyboard. $19.95

• plus $2 50 p&h

I □ Video Display Board kit lets you generate a sharp
r professional 32 or 64 characler by 16 line upper and

I lower case display on your tv screen or video monitor—
dramatically improvmq your unexpanded $99 95 ELF II
(Fits mside ASCII Keyboard cabinet ) $89.95
plus $2 p&h

□ ELF II Tiny BASIC on cassette tape Com
mands include S AVE LOAO ± x -=■ () .

26 variables AZ LET. IF/THEN. INPUT. PRINT. GO TO
GO SUB RETURN ENO. REM. CLEAR LIST RUN.
PLOT PEEK POKE Comes luliy documented and in-
cludes alphanumeric generator required to display
alphanumeric characters directly on your tv screen with-
out additional hardware Also plays tick-tack-toe plus a
drawing game lhal uses ELF ll s hex keyboard as a |oy
slick 4k memory required $14.95 postpaid

□ Tom Pittman s Short Course on Tiny Basic tor ELF II.
$5 postpaid

□ ELF-BUG™ Deluxe System Monitor on cassette
tape Allows displaying the contents ot all registers on
your Iv at any point in your program Also displays 24
bytes ol memory with lull addresses blinking cursor
and auto scrolling A must lor the serious programmer'
$14 95 postpaid

□ Text Editor on cassette tape gives you the ability to
insert, delete or edit lines and words Irom your programs
while they are displayed on your video monitor (Add
printer and you can use ELF. II to type error-lree tellers
plus insert names and addresses trom your mailing list )
$19.95 postpaid

□ Assembler on cassette tape translates assembly
language programs into hexidecimal machine code lor
ELF II use Mnemonic abbreviations lor instructions
(rather than numerics) make programs easier to read
and help prevent errors $19.95 postpaid

□ Disassembler on cassette tape lakes machine code

programs and produces assembly language source list-
ings lo help you understand and improve your programs
$19 95 on cassette lape

SAVE $9.90 Text Editor Assembler & Disassembler
purchased together only $49.95! (Require Video Dis-
play Board plus 4k memory )

□ ELF II Light Pen. assembled & tested $7.95 plus $1
p&h

□ ELF II Color Graphics & Music System Board kit

$49 95 plus $2 p&h

□ ELF ll connects directly to the video inpul ol your Iv
set without additional hardware To connect ELF ll lo
your antenna terminals instead order RF Modulator
$8 95 postpaid

Coming Soon: A O. D-A Converter Controller Board
and more'

Name

City

DEALER INQUIRIES INVITED

— _J

iS Reader Service— see page 227

Microcomputing, October 1979 1 43

SW3

SW2

SW1

SWO

Bit Rate

150

110

134.5

300

2400

4800

1/16 of EXT CLK

600

440

Non Standard

1200

9600

19.200

1/16 of EXT CLK

Jumper

-Bit Rate

SW3 = 0

SW3 = 1

7 200

28 800

'Depends on jumper

3 600

14 400

position

1 800

7 200

F10

200

800

e.g., Jumper at F6

F14

300

then 0100 1800 bps

1100 7200 bps

Table 3. Bit-rate outputs for circuit shown in Fig. 10.

♦5V

Fig. 9. 555 bit-rate clock for hard-copy terminal.

Fig. 10. Bit-rate generator based on the MC14411P.

quires a clock which is 64 times
the desired bit rate. While I sup-
pose I could have used the
555-type clock, I chose to use
the CMOS bit-rate generator
shown in Fig. 5 for the following
reasons.

1 . 1 wanted some flexibility to
try higher bit rates than 300 bps
normally used with this cas-
sette recording standard.

2. 1 felt that the stability of a
crystal-controlled clock was
important to the proper per-
formance of the cassette re-
cording technique.

3. I had bought some 307.2
kHz surplus crystals for 25$
each.

A source of reasonably priced
crystals is what really makes
the circuit in Fig. 5 practical.
Unfortunately, crystals in the
required frequency range tend
to be expensive. If anyone has a
source for low-cost 307.200 kHz
crystals, please write and let
other Microcomputing readers
know where they can be ob-
tained.

One other alternative is to
use the crystals for the
MCI 441 1 P or 34702 divider chip
to produce a 307.2 kHz signal.
2.4576 M Hz divided by 8 is 307.2
kHz, while 1.8432 MHz divided
by 6 is 307.2 kHz. Still another
possibility is to use a CD4040
12-stage binary counter and a
2.4576 MHz crystal in a circuit
similar to that of Fig. 5. It may
be necessary to try a number of
different capacitor values to
get a 2.4576 MHz crystal to
work in the circuit shown in Fig.
5. The first three stages of the
CD4040 will divide the 2.4576
MHz signal down to 307.2 kHz,
leaving nine stages to produce
the outputs shown in Fig. 5
(note that only seven stages are
needed).

Another recent project in-
volved the design of a serial in-
terface for my BIT 483 comput-
er. This interface is based on an
AY5-1013 UART, and I wanted 1
to include a reasonably flexible
bit-rate generator on the card.
The design goals for the bit-rate
generator portion of the circuit
include:

(1) A variety of bit rates had to
be available so that terminals
operating at 110 bps or 300 bps,

and CRTs operating at 2400 bps
or 9600 bps could be easily ac-
commodated.

(2) It should be very easy to
switch between bit rates.

(3) The circuit should be
small since not much board
space is available.

Clearly, only the MC14411P
or the 34702 fits all the design
requirements. The 34702 would
appear to be the best choice
because it includes a multi-
plexer that is required to satisfy
design goal number 2. The
34702 with crystal currently
costs about $22, while the
1441 1 P and crystal is about $17.

However, at the time I was
designing the circuit no “hob-
by” type suppliers offered the
34702 for sale. The only chip
readily available was the
1441 IP from Tri-Tek. Tri-Tek
has always provided me with
good service and quality parts.
Therefore, based on price and
availability, I decided to use the
MC14411P. A low-cost CMOS
multiplexer was added to the
bit-rate generator to allow a set
of DIP switches to choose one
of the 14 bit rates from 1441 IP
as the bit-rate clock.

The resulting circuit is
shown in Fig. 10, while Table 3
lists the bit-rate frequencies
available from the circuit. Be-
sides the MC14411P and its
crystal, the circuit includes a
CD4051 digital multiplexer and
a 2N3904 transistor to buffer
the output of the 4051. While
this transistor might not be
strictly necessary, I felt it was a
good idea to include it, espe-
cially if more than one UART
was to be driven by the circuit.

The four DIP switches used
to select the bit rate and the ex-
ternal clock input are not
located on the same board as
the bit-rate generator. There-
fore, resistors were inserted in
series with each input lead to
protect the CMOS circuits
when power was applied to one
board but not to the bit-rate
board.

Under these conditions the
CMOS circuits could be
damaged if these resistors
were not present. The external
clock input, pin 4 of the
CD4051, is a useful feature be-
cause it allows circuits that

1 44 Microcomputing, October 1979

generate their own clock sig-
nals, such as the Bit Boffer 7 , to
be used with the UART on this
interface board.

Table 3 shows that there are
16 different bit rates available
from the circuit shown in Fig.
10. Some of you are probably
wondering how an 8-input
multiplexer can be used to
select an output from 16 inputs.
The trick is to use SW3 to
switch the MC14411P from its
XI 6 to its X64 mode. In the X64
mode the frequency generated
at any pin of the MC14411P is
four times the frequency gen-
erated at that pin in the X16
mode. For example, the F„ out-
put, which generates a 150 bps
clock (2400 Hz) in the X16 mode,

pin-compatible devices listed
in Table 1. On the other hand,
as we have seen, there are
many different ways to build
the UART clock.

This article, and particularly
Table 2, should help you select
and design the bit-rate clock
that will be best suited to your
next UART application. Al-
though Table 2 does not list all
the bit-rate generators current-
ly being produced, it does in-
clude those of greatest interest
and availability to the computer
hobbyist. ■

References

1. D. Lancaster, TV Typewriter
Cookbook, Howard W. Sams,
Indianapolis IN 1976.

MCI 441 IP bit-rate generator mounted on serial interface board.
The circuit shown in Fig. 10 is located near the crystal on this
board. The 24-pin 1C is the MCI 441 IP; immediately next to it is the
CD4051 multiplexer. Other circuits on the board include a UART
(the largest 1C), a parallel input port and bus drivers for my surplus
minicomputer (a BIT 483).

will generate a 600 bps (9600
Hz) in the X64 mode. Since the
external clock input does not
come from the MC14411P, it is
not affected by SW3 being
opened or closed.

Conclusions

You may be tempted to
forget about the bit-rate clock
because it is an auxiliary func-
tion to the UART; however,
proper operation of a serial
communication circuit is highly
dependent on the reliable oper-
ation of the clock circuit. Se-
lecting a UART is a simple mat-
ter of obtaining one of the many

2. The Communications Hand-
book, Microdata Corporation,
Irvine CA 1973.

3. G. Pickles, “Who’s Afraid of
RS-232?’’ Kilobaud No. 5, p. 50.

4. N. K. Batra, “Programmable
Baud Generator for an 8080
Works off the System’s Clock,”
Electronic Design No. 16,
August 2, 1977, p. 104.

5. K. Rallapalli, “Programmable
Bit-Rate Generator,” Interface
Age Vol. 2, Issue 5, April 1977,

p. 68.

6. R. Derynck, “Super Terminal!”
Kilobaud No. 15, March 1978, p.
48.

7. D. Lancaster, “Build the Bit
Boffer,” Byte No. 7, March
1976, p. 30.

Main/Frames ... $200

For Easy Troubleshooting on No-Front-Panel Computers
DDI’s FRUGAL FRONT PANEL Series Kits Include:

DISPLAY-SENSE BOARD for S-100 Bus .... *99.95

REMOTE HEX PANEL * 74.95

REMOTE BINARY PANEL *69.95

All Are of Highest Quality Construction and Design.
Fully Soldermasked and Silkscreened.
Assembled Versions Available.

Full Line of COMPUTER CANOPY VINYL DUST COVERS.
High Quality, Good Looking Protection. Priced from *9.95.
Covers Available for Most Popular Microcomputers
and Peripherals. Write for FREE Brochure.

NEW PRODUCTS Coming September 1979:

• 32 PORT S-100 CONTROLLER BOARD With Matching
Solid State Sensor and Drive Module Subsystems.

• 64K S-100 PARITY BOARD • WRITE for Advance Specs

for These Industrial-Quality Boards.

Digital Dynamics Incorporated
Department K, 31 0C Breesport
San Antonio, Texas 78216

512-341-8782

^D37

iS Reader Service— see page 227

Microcomputing, October 1979 1 45

(•) rondure company the computer room

SPECIAL GE TERMINET DATEL SELECTRIC

Printer for your Microcomputer 300 PRINTER (IBM Selectric Mechanism)

Pin feed— 9” paper

• 80 Print positions

• Receive only

• ASCII code

• RS-232 interface

• 30 CPS

• Upper & lowercase

• Shipping wt. 75#

(used)

(good working condition)

Will run on serial RS232 port of most
micros including TRS-80.

$450.00

ASCII SELECTRIC

Printer Mechanism: Heavy
duty input/output. Series
745.

TESTED WITH
NEW
ASCII

ELECTRONICS

Weight: 120 lbs. Dimen-

sions: 29”Hx35”Wx33 ,, D.
Print Speed: (14.8 charac-
ters per second)

Platen: 15" wide, pin feed
or form feed device option-
al (132 print positions).

SPECIAL SALE
$875.00

Parallel output only— 15
characters per second ac-
cepts 7 bit ASCII parallel
w/strobe & prints on Selec-
tric. The unit still works as
a typewriter in off-line
mode.

ASCII Selectric with ASCII parallel electronics.
Immediate Delivery -Shipped from inventory

ASCII Keyboard

(used)

with enclosure

$35.00

NOTE:

WE HAVE FLAT-PACK
ACOUSTIC

Modem pickup $ 1 9 50

Even though market SOLD OUT
in catalog— we've got more.

New

RS232 Connectors

Male -3.50
Female -4.50
Covers — 1.75

SHUGART

MINIFLOPPY
DRIVE

NEW PRICE
$325.00 ea.
Model SA-400

USED FANS

Muffin-8.00
Sprite -4.00

NEW Novation Modems & Couplers

4102A— Acoustic— Originate $275.00

41 03A— Acoustic— Ans/Orig $295.00

4102-Hard Wire-Orig $340.00

4103B— Hard Wire— Orig. & Auto Answer . . . .$385.00
41 13B— Hard Wire— Auto Answer Only $365.00

USED

POWER SUPPLY
$15.00

V 5, 16.5, 6,-3
A 12, 6, 2, 1

USED Mh

ANS./ORIG.

149.00

USEDOMNITEK

NEW

CAT

MODEM

195.00

ORIG.

ONLY

95.00

V 5, 12, -12
A 3, 6, 3

NEW

POWER

SUPPLY

25.00

ORDERING INFORMATION:

We ship the same day we receive a certified check or money order.
Texas residents add 5% sales tax. Please call if you have a question.
Write for our CATALOG of many parts, terminals, printers, etc.

AM items subject to availability. Your money returned if we are out
of stock.

SHIPPING INFORMATION:

Modems: $2.00 each; 2 for $4.00 UPS.

Large Items & Parts: Specify Freight or Air Freight Collect
Foreign Orders: Add appropriate freight or postage.

We now take Master Charge and Visa orders. Specify full number,
bank number and expiration date.

1 46 Microcomputing, October 1979

is M32

MULLEN

EXTENDER

H8 EXTENDER BOARD, DESIGNED BY BOB MULLEN

(his S-100 Extender Board has helped thousands of
Computerist get their S-100 systems, up and running)

♦trademark of HeathKit Corp.

Features:

JUMPER LINKS IN POWER
LINES, ALLOW FUSING &
CURRENT MEASUREMENT

FORMED CONNECTOR LEADS,
FOR EASY SCOPE PROBE
ATTACHMENT

LABELS, IDENTIFY SIGNAL
LOCATIONS

HTB-1

KIT $39

OUR S-100 PRODUCTS'

TB-2

KIT $39

EXTENDER/LOGIC PROBE

f CB-1

KIT $129.00
ASSM $179.00

RELAY/OPTO-ISOLATOR CONTROL BOARD

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Reader Service— see page 227

Microcomputing, October 1979 147

Microcomputing, October 1979

mmm&m

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Reader Service— see page 227

Microcomputing, October 1979 1 49

Exploring the
Inequality of Bus Buffers

All buffer chips are not created equal. If you don’t know your 74366s from your 8T95s, for ex-
ample, here’s your chance to read and learn more about buffers.

John R. Cameron
PO Box 1517
Palo Alto CA 94301

T his article has the solution
for a bus buffer problem
you may not have recognized
. . . yet. But first, let me de-
scribe the situation.

One of the common charac-
teristics of a flexible microcom-
puter system is the use of a
bus, a collection of many, more-
or-less parallel conductors with
sockets that connect the CPU

card (central processing unit
board) to one or more auxiliary
cards. The ability to change the
number or type of auxiliary
cards by merely plugging them
into sockets on the bus pro-
vides the adaptability many of
us need in our home or
business computers. It also
produces often difficult prob-
lems of compatibility.

How It Works

In practice, the use of a bus
requires that most input or out-

put lines from the CPU be con-
nected to several different aux-
iliary cards’ outputs or inputs
at once. However, the CPU
chips in use today cannot pro-
vide a sufficient output current
to reliably service much more
than one LSTTL (low-power,
high-speed Schottky) load.

Furthermore, the various
auxiliary boards’ outputs would
try simultaneously to send dif-
ferent signals to the CPU’s in-
puts. On some bus systems
(i.e., 16-bit S-100), the CPU’s in-

put and output must be multi-
plexed together on a single set
of eight or 16 lines so that
either input or output, not both,
is occurring at one time.

These traffic flow considera-
tions are all solved by the use of
several different types of bus
buffer devices that amplify the
current flow capability of a
signal put on the bus and, in
some cases, turn signals off
when they are not desired.

General characteristics of
the integrated circuits used as

Device Number

Buf.

Inv.

Out. 1
H L

Inp. 1
H

P.S. 1
/Buf.

/Buf.

Comp.

Group

Notes

7404

0.4

.04

1.6

5.5

2-state

74LS04

0.4

.02

0.4

1.1

2-state

7406, 07, 16, 17

Y/N

<25

.04

1.6

7.0

open collection

74125, 126

5.2

.04

1.6

15.5

74LS125, 126

2.6

.02

0.4

5.3

74LS240

.02

0.2

4.1

Schmitt trigger

74LS241, 244

.02

0.2

5.4

Schmitt trigger

74365, 367

5.2

.04

1.6

14.2

74LS365, 367

2.6

.02

0.4

4.7

74366, 368

5.2

.04

1.6

12.8

74LS366, 368

2.6

.02

0.4

4.3

8093, 94

5.2

.04

1.6

15.5

8095, 97

5.2

.04

1.6

14.2

8096, 98

5.2

.04

1.6

12.8

81LS95, 97

2.6

.02

0.4

3.3

economical

81LS96, 98

2.6

.02

0.4

2.6

economical

8T95, 97

5.2

.04

0.4

16.7

premium

8T96, 98

5.2

.04

0.4

15.8

premium

S-100 standard

>24

<.08 <0.8

Table. 1. Parameters of various bus buffers. Data for this table was collected from Signetics (1978) and National Semiconductor (1976)
TTL data manuals.

1 50 Microcomputing, October 1979

bus buffers and their applica-
tion have been described in
Kilobaud Klassrooms by
George Young (May 1978, p. 54)
and Peter A. Stark (Aug. 1978, p.
36). Briefly, they are TTL chips
connected between the CPU
chip or auxiliary board circuits
and the bus lines.

The chip contains several in-
dependent buffers, each with
input and output pins. The
signal on the output pin is
either the logical equivalent (1
or 0) of the signal on the input
pin or its logical inverse, de-
pending on the chip used.

Most have the additional
capability of turning their out-
puts to a third state, off or high
impedance, where they do not
influence the bus line. Another
buffer can then send its data on
that line. This is controlled by
the signal on one or two other
pins on the chip referred to as
chip enable or disable pins.

The proposed S-100 bus stan-
dard of the IEEE Computer
Society Microprocessor Stan-
dards Committee calls for most
status and control signals (14)
as well as all address (16) and
data lines (16) to be buffered
with such three-state devices
on the CPU card to allow multi-
ple auxiliary cards, any one of
which can control the bus by
shutting off normal CPU con-
trol commands (direct memory
access).

The Problem

A problem arises when the
buffers on the CPU card or on
the auxiliary cards (if these
even have buffers) are in-
capable of providing sufficient
current to reliably maintain a
particular bus line and all the
inputs connected to it at the
desired logic voltage level.
Typically, an address line buf-
fer required to output a logic 1
(2.0 to 5.0 volts) will not source
enough current to supply the
many address inputs on aux-
iliary cards (quite possibly over
50 due to the lack of input buf-
fers on many auxiliary boards),
and the voltage then drops
below 2 volts.

Note that at the high rates of
signal change occurring in fast
microprocessors, long bus
lines have an electrical

characteristic such that they
require “filling up” with cur-
rent. Such a characteristic,
combined with insufficient cur-
rent output, produces an uncer-
tain logic level (0.8 to 2.0 volts)
along the bus’s address line.
Quite simply, your program
may occasionally go flying off
to parts unknown with no ob-
vious provocation.

The Solution

Do not despair: The solution
to this problem or its preven-
tion through prophylactic
analysis of your system is
direct and easy to understand.
You simply determine the out-
put current capabilities and in-
put current requirements at
both low and high logic levels
for each significant bus line in
your system.

require the same amount of in-
put current as do the 7404 and
74LS04 devices, respectively.

The unsigned output and in-
put currents (I) in Table 1 are in
milliamperes (mA) and are
specified for a high logic level
of 2.4 volts and a low logic level
of 0.4 volt. This provides a safe-
ty margin of 0.4 volt at both
logic levels. Power supply cur-
rent is in mA for the worst-case
no-load situation.

Cost per buffer is based on
single unit discount prices.
Buffer specifications in the pro-
posed standard for the S-100
bus (published in Dr. Dobb’s
Journal , number 25, p. 40, by
George Morrow and Howard
Fullmer) are given on the bot-
tom line, and those bus buffer
chips that fulfill these specifi-
cations are indicated by an

Fanout Number

High

Low

Device

0.04 mA

0.4 mA

1.6 mA

Number

Unte.

Term

Unte.

Term.

7404

74367

130

74LS367

81LS97

8T97

130

120

Table 2. Some typical fanout numbers.

If each line is buffered on
both input and output ends
with typical devices, then all
the information you need is in
this article. If some of your
system’s bus inputs are not
buffered, you will have to look
up the necessary information
on input current requirements
for each chip on that line and
add them up for both logic
levels.

Relevant data on typical bus
buffer chips for this analysis is
provided in Table 1. All of these
devices are three-state except
for those in the first three lines,
which are ordinary two-state or
open collector as noted.

Open collector devices re-
quire a pull-up resistor to the
positive logic level in order to
source any significant output
current (logic-high output), and
the value of this resistor deter-
mines, up to a point, the max-
imum value of this current.
Most TTL or LSTTL devices will

asterisk in column 10,

Schmitt-triggered devices
have reduced noise sensitivity,
and these devices may be espe-
cially useful for input condi-
tioning. Transceivers (used on
bidirectional lines) have not
been included, and low-power
versions of 80- (80L-) and 81 LS-
(71 LS-) are not usable for micro-
computer buses due to insuffi-
cient output currents.

A convenient characteristic
of certain bus buffer chips is
compatibility. All of the three-
state chips with six buffers
listed are pin-for-pin compati-
ble (Comp. Group 4 in column
10), if attention is paid to the
sense of the data (Inv. ? in col-
umn 3) and the implementation
of the enable/disable pins
within a particular group.

Three-state devices on the
same line in Table 1 differ only
in the latter characteristic, and
the use of 5 or 7 and 6 or 8 as the
last numeral in their device

number clarifies the compati-
bility in this respect. Such com-
patibility allows you to simply
exchange devices in a socket if
more output current capability
or less input current loading is
required for that chip.

Unfortunately, six buffers
per chip do not service 8- or
16-bit parallel lines very conve-
niently. The worst compatibility
problem where no buffers exist
might require alteration of the
circuit to include them or the
purchase of a different board, if
there is a choice.

Thus, the presence of both
input and output three-state
buffers on a board increases its
flexibility. It also increases its
power consumption and cost.
These two considerations are
treated on a per buffer basis in
columns 8 and 9 of Table 1.

Some Fine Points

Table 2 describes some com-
mon bus load capabilities (ex-
pressed in fanout numbers) for
the more frequently used bus
buffer chips. It also points out
the effect of having a resistor
network termination on each
bus line.

The maximum number of in-
puts serviced by some common
buffers is given according to
the input currents at high or low
logic levels, with or without a
resistive termination network.
The typical network chosen
consists of a 330 Ohm resistor
to +5 volts and a 470 Ohm
resistor to ground.

The signed output current of
such a network for a particular
bus line voltage is the sum of
the signed currents for each
resistor determined using the
voltage drop across each —
signed current = (line voltage
minus 5 or 0) divided by the
resistance. Note that these
fanout numbers only apply if
the input devices used require
less than 0.8 volt for low and
greater than 2.0 volts for high
logic levels. Some non-TTL-
compatible devices have more
stringent requirements.

The network chosen tends to
keep the line at 3 volts, which
benefits a high logic output
(pull-up) but loads a low logic
output at 0.4 volt to the extent
of 13 mA (33 LS input equiva-

Microcomputing, October 1979 151

lents). Such a passive termina-
tion network helps reduce
noise and ringing on the bus,
which can give erroneous
signals at higher clock speeds;
unfortunately, this comes at
the price of drastically increas-
ing the load on a buffer’s out-
put signals to a bus line and, as
Table 2 shows, the number of
inputs allowed on that line.

The wisdom of using input
buffers that require less input
current at a low logic level (0.4
mA) is also demonstrated. Note
that when most Tri-state buf-
fers are disabled, their inputs
source far less current (provide
about one tenth their normal
enabled load to a low logic level

signal).

Addition of a buffer to a
signal line adds a small amount
of delay to the signal’s propa-
gation, which could bea signifi-
cant consideration in a high-
speed system. The maximum
propagation time for the three-
state devices listed (from a
disabled state to output high or
low) is from 15 to 37
nanoseconds. This variation
among different device types is
not much more than that seen
with individual devices of the
same type. However, premium
devices can save several
nanoseconds in propagation
time when the device is con-
tinuously enabled.

The 8T- series of devices has
the reputation of being a
premium series in terms of
power, speed and noise insen-
sitivity. These devices also cost
twice as much as, and use more
power than, other devices with
almost identical published
parameters.

Certain difficult-to-specify
qualities of this series may
make it better for critical ap-
plications. In one experience, a
noisy 2708 EPROM (16K) board
gave incorrect output data
about one time in 10 4 with
several 74LS367 or 74367 out-
put buffer chips but worked
perfectly with several different
8T97 chips.

Apparently, the 8T97 was
able to better differentiate
proper logic levels from noise-
induced glitches finally found
to be due to a bad capacitor on
a voltage regulator output.
Replacement of the capacitor
was a more satisfactory solu-
tion in this case, but the 8T97s
are still there to increase the
margin of error.

I wrote this article after com-
piling information on bus buffer
chips, which is useful to me in
designing or modifying boards
for my computer. I hope it will
also help others in this way or,
at least, expand understanding
of these not very elaborate but
still important devices. ■

TRS-80 COMPUTING

nonprofit newsletter

12 Issues For $15.00

and now (US)

PEOPLE’S SOFTWARE

at popular prices

• Tape 1: 34 Level II or 24 Level I (indicate which you
want) business, home, educational. $7.50

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• Tape 3: People's Pascal program development system.
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• Tape 4: 21 misc. Level I programs. $7.50

• Tape 5: 24 misc. Level II programs. $7.50

Add 50$P&H each tape, CA residents add tax

* COMPUTER
- INFORMATION
^ C104 EXCHANGE

Box 158 San Luis Rey, CA 92068

\ /

TRS-80 disk software

DATA BASE MANAGER You can maintain a data base &
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parameters & report formats on-line. Almost use up the
required 32K memory. $49.

ACCOUNT manage client accounts & account receivable.
Automatic billing & transaction recording. 32K req. $59.

WORD PROCESSOR Specifically designed for the TRS-80.
Written in BASIC. No special hardware and text limit. $39.

INVENTORY 9-digit key for fast on-line random access.
Reports give order info, performance summary, etc. $39.

MAIL print reports & labels sorted by any field. Random
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KEY RANDOM-ACCESS UTIL hashing, blocking, buffering, auto
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Arlington, MA 02174

THE

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(301)461-2721
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Coming Next:

A Spooler For the TRS-80

TRS-80 ^EVEL II ^

and Disk ^Programs

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chained programs that permits model estimation using
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Linear Programming $29.95

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Transportation Algorithm $29.95

Heuristic Line Balancing $29.95

Stat. Pack— medium, mode, mean (avg., harmonic,
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Limited by BASIC’s logical structure?

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SBASIC supports 5 types of loop structures,
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Hastings, Michigan 49058
(616) 945-5334

(Dealer inquiries invited ) ^ ui2

1 52 Microcomputing, October 1979

HYNES AUDITORIUM, PRUDENTIAL CENTER, BOSTON

Interested In Personal Computers?

Interested In Business Systems?

FRI

COME

■AST

(ness

This is the place for you ! You’ll meet and talk with
hundreds of manufacturers, distributors and retailers.,
all showcasing their new 1980 Micro, Mini and Small
Computer Systems.

You’ll see them all. ..Radio Shack, Pet, RCA,
Compucolor, Heathkit...you name it! All the major
terminal and peripheral companies too, plus software
developers magazine editors and book publishers. Yes,
it’ll be the largest showing of personal computer
hardware, software and services ever assembled in
the Northeast!

You’ll be enthralled, entertained and educated. You’ll
see computer art, graphics and animation. You’ll hear
computer synthesized music, watch computerized
amusements, play electronic and video games
and attend scores of free tech talks
briefings given by internationally
recognized speakers. And you may
win a free computer given away
as a door prize! Don’t miss the
largest gathering of computers
and computerists! No
pre-registration necessary.

Tickets available at the door.

Adult admission $5.00.

Interested in Business Systems? This will be your one
opportunity to see all of the Mini, Micro and Moderate
Sized Computer Systems under one roof Your
attendance at this show is a must if you, or your
company, are contemplating the purchase of any type
of computer or office equipment.

You’ll see them all. ..the big ( and small) names in
computers, data and word processing eqiupment,
peripherals and software. You’ll attend dozens of free,
easily-understood briefings on how computers can
help you in your business or profession.

So if you’re considering a computer or computer-
related service... starting your own computer
business or changing your job within the
computer industry. ..or if you’d just like to learn
about computers as they relate to
your personal life and to your
business or profession, come to
the show to see the
Computerized World of
Tomorrow. ..Today. And bring
the entire family, It’s a fun-
filled educational experience.
No pre-registration necessary.
Tickets available at the door.
Adult admission five dollars.

Brookline Village, MA 02147 (617) 522-4467

Produced by

Northeast Expositions, P.O.

Box 678,

tS Reader Service— see page 227

Microcomputing, October 1979 153

Glen A. Popiel

4005 Tanglewood N. Apt. 493
Palm Beach Gardens FL 33410

Elfish Ideas

Elves, by nature, are quick. Here are some ways to hasten your Elf’s I/O.

A re you tired of seeing serial
I/O interfaces for your Elf
that use only the Q register for
output and an EF line for input?

I don’t like the idea of tying
up valuable CPU time doing
timing loops for a Teletype. To
me, it is far easier to output or
input a byte using an I/O port
and have the device set a flag
line to tell me when it is done. In
this article, I hope to show you
a few ways to speed up your
Elf’s I/O without spending too
much money.

The circuit in Fig. 1 is a sim-
ple UART (universal asynchro-
nous receiver/transmitter) in-
terface. This circuit can be
used to interface almost any
serial I/O device to the Elf. I am
presently running this UART
circuit on my Elf with a Data-
point display running at 2400
baud with IK of memory. You
can even use this circuit as a
cassette interface by adding a
modem to the serial input and
output lines of the UART.

The UART is a TR-1602 from
Western Electric. Any similar
UART will work, however. The
TR-1602 requires +5 and -12
volts for operation. The trans-
mit and receive clocks must be
16 times the desired data rate;
so to run at 300 baud, for in-
stance, you would need a
transmit and receive clock fre-
quency of 4800 Hz. For a stable
clock, you could derive the
clocks from a crystal oscillator;
but in order to save money, an
NE 555 oscillator, shown in Fig.
2, will work fine.

The UART in Fig. 1 is con-

figured for a 7-bit word with odd
parity and one stop bit. The
UART, however, may be set up
for any word length from five to
eight bits, with odd, even or no
parity and with one or two stop
bits. My display is a 7-bit, odd
parity, ASCII device, so I will
confine my circuit descriptions
to this configuration.

The Transmitter

Data from the CPU is strobed
into the UART with a 62 instruc-
tion. This instruction places the
byte addressed by the X reg-
ister onto the data bus and sets
the N lines to 2. The N lines are
decoded by the 74154 into 16

discrete lines. The Elf can ac-
cess up to seven output and
seven input devices directly
from the N lines.

Pin 3 of the 74154 will go low
when the N lines are equal to a
2 and an output instruction is
being performed. This will
cause the byte on the data bus
to be loaded into the UART’s
transmitter buffer.

The UART has a two-char-
acter buffer, so a second
character may be loaded into
the UART while the first
character is still being sent. Pjn
22 of the UART provides TX
BUSY, which may be used to in-
dicate to the CPU that the

transmitter buffer is full and
that any further loading of data
into the UART will write over the
data in the buffer.

Positive true serial TTL data
comes out of pin 25 of the
UART. This can be used to pro-
vide RS-232 data. I am using the
Motorola 1488 and 1489 RS-232
interface chips, but any of the
interfaces described by Dr.
Mark Boyd in “Interfacing
Tips” ( Kilobaud , February 1978,
p. 72) should perform as well.

The Receiver

Positive true serial TTL data
is fed to the UART at pin 20.
Upon receipt of a character, the

Fig. 1. UART interface circuit.

1 54 Microcomputing, October 1979

♦5 V

Fig. 3. Priority encoder circuit.

Fig. 2. NE 555 oscillator.

ADDR.

INSTR.

0000

loop if TTY is busy

0001

loop address

0002

out

output immediate byte

0003

ASCII ‘H’

0004

loop if TTY is busy

0005

loop address

0006

out

output immediate byte

0007

ASCII T

0008

loop if TTY is busy

0009

loop address

000A

out

output immediate byte

000B

ASCII ‘space’

oooc

bn3

branch if key has not been hit

000 D

branch address

000 E

idl

idle CPU if key has been hit

Fig. 4. Program to test serial interface.

error conditions, if any, are in-
dicated, and pin 19 of the UART
provides RX CHAR, indicating
to the CPU that a character has
been received. The UART re-
ceiver data is gated onto the
data bus with a 6A instruction
(N lines = 2) and written into
the memory location specified
by the X register.

The EF Line Encoder

The circuit shown in Fig. 3 is
a 16-line to 4-line priority en-
coder. This takes the input flag
line with the highest priority
and provides the binary code
for that line on the output of the
encoder. Line F has the highest
priority, and line 0 has the
lowest priority.

In addition, a fifth line, which

I call INT, goes low whenever a
request for the CPU is made via
the input flag line of the en-
coder. This may be used to pro-
vide an interrupt to the CPU.
Care must be taken if the CPU
is not programmed to handle in-
terrupts because the CPU may
tend to walk all over your pro-
gram in core. If you are not go-
ing to run under interrupt con-
trol, I suggest that you leave
the INT line from the encoder
disconnected.

Summary

A short program to test the
serial interface is shown in Fig.
4. It will fill the screen with “HI”
until you hit a key. The serial in-
terface and priority encoder,
when used together, increase

the Elf’s I/O flexibility. No
longer will the CPU be twiddling
its thumbs in a timing loop
waiting for a Teletype.

I am presently writing a small
system monitor for my Elf,

using my present system and a
cassette interface as well.
Anyone interested in a program
listing of the monitor, when
completed, should write me for
more information.*

AD-68A ANALOG-TO-
DIGITAL CONVERTER

• 8 analog input channels
•Occupies one SWTPC 6800 I/O

slot

• Quality components and PCB

• Complete documentation

• 90 day full warranty
•Assembl ed a nd teste d

$39.95 £9 gg

Available from your local dealer or
factory direct. Write for additional
information.

^ 124

Innovative Technology

510 Oxford Park
Garland. Texas 75043
(214) 270-6393

leMel n-sp2edup
computer operation

Install a clock control board and CLOAD, CSAVE,
and run programs 50% faster without the use of
switches.

□ Basic statement OUT 2S4.1 changes the TRS-80 to a faster 2.66 mhz
operating rate. OUT 254,0 retirns normal (slower) 1.77 mhz operation.

□OUT statement can be entered at the keyboard or included in your soft-

□ Easy to install 1.5" 1 2.5” board fits neatly inside the keyboard unit.
□Works with or without the TRS-80 expansion interlace.

□ Allows easy loading and speedup ol your present Bask and machine
language (system) programs.

L TRS-80 automatically sets to tts normal operating speed when power is first
applied.

□Speed changes will not disturb memory-no program crashes.

“This is not a kit. The board comes fully (and
beautifully!) assembled*. . . CIE TRS-80 Bulletin,
May 79

ASSEMBLED and TESTED— $24.95 ppd

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106 SNYDER DR.
MATHER , CA 96655

iS A98

(916) 362-3627

THE

COMPUTER EXCHANGE

2217 Freeland Way -' C146
Dallas, Texas 75228

BUY/SELL

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NEEDED INFORMATION

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tS Reader Service— see page 227

Microcomputing, October 1979 155

SAVE SAVE SAVE SAVE SAVE SAVE SAVE SAVE SAVE SAVE SAVE SAVE SAVE SAVE •

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OC-10 Cassettes
©Verbatum Diskettes

DISK DRIVES NOW IN STOCK!

REG.

OUR

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PRICE

TRS-80 Complete System

Level II -4K RAM

$ 698.00

628.20

TRS-80 Complete System

Level I1 16 K RAM

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Expansion Interface

$ 299.00

$ 269.10

Pertec FD2000 Disk Drive

$ 495.00

$ 385.00

BASF 6106

S 599.00

$ 495.00

Centronics 779 Printer

$1599.00

$1299.00

Centronics 101 Printer

$1595.00

$1400.00

Anadex DP-8000 Printer

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995.00

Centronics PI Printer

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Trendata 1000

$1495.00

SI 295.00

Memory Unit (Kit)

$ 199.00

96 00

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C-10 Cassettes 5

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NEW & IMPORTANT SOFTWARE

Lower Case conversion - Level II - Tape - $19.95

• Type text on your keyboard just as you would on your
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• For use with hard copy devices with a lower case
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Loan Amortization Schedule - $19.95

Level II - Tape/Disk - 16K -

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• Prints one period or entire schedule

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Real Estate Package - Level II - Disk - 16K $34.95

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* # of Bedrooms

Household Inventory - Level II - Tape - 16K - $19.95

• For Insurance claims

• Classified by Room, Purchase date. & Price

• Add, Detete, Change Routines

Business software

for TRS— 80

Business Inventory- Level II-32K-2 Disk Drives $49.95

• Random Access - Double Precision - 650 Item

• FIELDS

Item Description. Unit cost. Selling Price. Transaction
date, Catalog #, P.O. #. Qty on Hand. Reorder level.
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• Reports Printed -
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Re-order List - On-order List - Out of Stock List
Dept/Sales Report - Inventory Worksheets
Comprehensive Business Data Base - Level II -
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• Account Number Generation (Check digit)

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Payroll (115 employees) - Level II - Disk - 32K $49-95

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1 56 Microcomputing, October 1979

CT-50 freo^nc^counte^^ ^

SAtf

FREQUENCY COUNTER KIT
Outstanding Performance

_ Incredible Price
CT-50

89 !

The CT-50 is a versatile and precision frequency counter which will measure «eaaout aaigi

frequencies to 60 mHz and up to 600 mHz with the CT-600 option. Large Scale stSy^oTc

Integration, CMOS circuitry and solid state display technology have enabled this counter to compensator

match performance found in units selling for over three times as much. Low power input bnc. i n

consumption (typically 300-400 ma) makes the CT-50 ideal for portable battery operation Overload sow

Features of the CT-50 include: large 8 digit LED display. RF shielded all metal case, easy Se ™^ iv,, y ' eSS

pushbutton operation, automatic decimal point, fully socketed 1C chips and input protection Po ™ er z 110VA(

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easy assembly Clear, step by step instructions guide you to a finished unit you can rely on. ics 13 units a

Order your today!

CT-50. 60 mHz counter kit S89.95 CB-1 . Color TV calibrator-stabilizer

CT-50WT, 60 mHz counter, wired and tested 159.95 DP-1. DC probe, general purpose probe

CT-600. 600 mHz scaler option, add 29.95 HP-1 . High impedance probe, non-loadir

SPECIFICATIONS:

Frequency range 6 Hz to 65 mHz. 600 mHz with CT-600
Resolution l0Hz(« 0 1 sec gate. 1 Hz(>/ 1 sec gate
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Accuracy adjustable to 0 5 ppm
Stability: 2 0 ppm over 10 to 40 C. temperature
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Input BNC. 1 megohm 20 pf direct. 50 ohm with CT-60C
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Sensitivity less than 25 mv to 65 mHz. 50-150 mv to 600
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Size 6" x 4" x 2 ". high quality aluminum case. 2 lbs
ICS 13 units all socketed

CAR
CLOCK

The UN-KIT. only
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Here's a super looking, rugged and accurate auto
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Under dash
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12/24 hour clock in a beau-

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DC-11 clock with mtg. bracket $27.95

DM-1 dimmer adapter 2.50

VIDEO TERMINAL

A completely self-contained, stand alone video ter-
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RE 3216, terminal card $149.95

RE 6416, terminal card 189.95

Lower Case option, 6416 only 13.95

Power Supply Kit 14.95

Video /RF Modulator, VD-1 6.95

Assembled, tested units, add 60.00

PRESCALER

Extend the range of your
counter to 600 mHz. Works
with any counter Includes 2
transistor pre-amp to give super sens, typically 20
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PS-1 B, 600 mHz prescaler $59.95

PS-1 BK. 600 mHz Drescaler kit 49.95

CALENDAR ALARM CLOCK

The clock that's got it all; 6- 5” LEDs. 12/24 hour,
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Size 5x4x2 inches

Complete kit. less case (not available)

DC-9 $34.95

"30 Watt i^mtTpV^R'^MP

Simple Class C power amp features 8 times power
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Max. output of 35 W. incredible value, complete with
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PA-1 , 30 W pwr amp kit $22.95

TR-1 . RF sensed T-R relay kit 6.95

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FM WIRELESS MIKE KIT

Transmits up to 300’
to any FM broadcast
radio, uses any type of
mike Runs on 3 to 9V
Type FM-2 has added sen-
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FM-1 kit $2.95 FM-2 kit $4.95

COLOR ORGAN/MUSIC LIGHTS

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VIDEO MODULATOR KIT

Converts any TV to video monitor
Super stable, tunable over ch 4-6
Runs on 5-1 5V. accepts std video
signal Best unit on the market'
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TONE DECODER

A complete
tone decoder on
a single PC board
Features: 400-5000

Hz adjustable range via
20 turn pot. voltage regulation. 567
1C Useful fortouch-tone decoding,
tone burst detection, FSK. etc. Can
also be used as a stable tone en-
coder Runs on 5 to 1 2 volts.
Complete kit. TD-1 $5.95

SUPER SLEUTH

A super sensitive am-
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up a pm drop at 15 feet'

Great for monitoring baby's room or
as general purpose amplifier Full 2
W rms output, runs on 6 to 1 5 volts,
uses 8-45 ohm speaker
Complete kit, BN-9 $5.95

LED BLINKY KIT

A great attention getter which alter-
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for name badges buttons, warning
panel lights, anything! Runs on 3 to
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Complete kit. BL-1 $2.95

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Reader Sen/ice — see page 227

Microcomputing, October 1979 1 57

Load Programs the
SIMPL Way

The author of this article has taken a cue from the maxi-computer boys and written a loader
for his system. It’s an idea that can be utilized to work on your micro, too.

Harold B. Combs
809 Englewood
Del City OK 73115

C omputers should be sim-
ple, I thought to myself as I
spent several months loading
BASIC from one tape, my As-
sembler from another tape and
my utility program from yet an-
other. I went through this time-
consuming ritual every time I
sat down to program, until I
finally got fed up. I decided
there must be a better way.
Therefore, I borrowed an idea
from the big computers and
wrote myself an IPL program.

IPL stands for Initial Pro-
gram Load. In the big machines
it is a bootstrap program to
load the monitor into memory.
But my program does much
more.

Now, when I want to pro-
gram, I just put the IPLtape into
my recorder, press play and
type XEQ. I can then ignore the
computer for a few minutes

knowing that when I return, it
will be ready to run BASIC or
Assembler at my option.

The Program

The program SIMPL is writ-
ten in 8080 assembly language
and is currently running on my
Sol-20 system with the Solos
monitor. SIMPL stands for Solos
Initial Multiple Program Load. It
loads into memory all programs
that follow it on the IPL tape,
until it finds a program named
END. It will then link BASIC, As-
sembler and the utility program
to my system monitor. There-

fore, all I have to do to run
either one is enter a two-letter
command. Finally, it will ask
the operator for the current
date and store this information
in a safe place for other pro-
grams to have access to.

The IPL Tape

The IPL tape is an important
part of SIMPL. The first file on
the tape is, of course, SIMPL;
after that you may have as
many files as you like (or have
memory for).

Remember that the last file
on the IPL tape must be named

END. This can be a dummy file
or an actual program, since the
file is loaded before a check is
made on the name. One rule
that must be observed in creat-
ing the IPL tape is to leave at
least three seconds of blank
space between tape files to al-
low time for the tape to stop
and get up to speed again. If
this is not done, you are likely
to experience recurring read er-
rors.

My IPL tape contains SIMPL,
BASIC, Assembler, my dump
program and a dummy file
named END, in that order. You
may want to put BASIC, fol-
lowed by one of your favorite
games, on your IPL tape; there-
fore, when SIMPL is finished,
not only will you have BASIC in
memory, but the game will also
be ready to run (see Example 1).

The System Date

The last thing SIMPL does is
to ask the operator for the sys-
tem date. This is usually the
current date and is entered in
MM/DD/YY format. Be sure to
include the slashes. The pro-
gram will accept any eight char-
acters for the system date and
make no check to see if it is

SIMPL D

4Cffff 032F

S.I.H.P.l.

Solos Initial Multiple Pro-gran Load

IPL1I Iff

IPL NOU IN PROGRESS

IPL 1 ff 20

SUCCESSFUL PROGRAM LOAD

IPL1I30

FILE NAME ! BASIC

IPL 1 020

SUCCESSFUL PROGRAM LOAD

I PL 1030

FILE NAME : ALS-8

I PL 1 0 20

SUCCESSFUL PROGRAM LOAD

IPL 1 03ff

FILE NAME < DUMPX

IPL 108#

SOLOS LINKAGE COMPLETE

IPL109I

ENTER SYSTEM DATE (MM/DD/YY)

02/22/79

IPL 1 #99

SYSTEM IPL NOU COMPLETE

SYSTEM CUSTOM COMMANDS

: UILL EXECUTE ALS-8 ASSEMBLER

! UILL EXECUTE BASIC INTERPRETER

DX ADDR1

ADDR2 : UILL DUMP MEMORY IN HEX ASCII FORM

Example 1. List of SIMPL messages from standard IPL.

158 Microcomputing, October 1979

9100 REN* ****************
9010 REN* SUBROUTINE TO GET SYSDATE

9020 REH*

9030 REH* SYSDATE IS STORED AT 51218 TO 51225 (DECIMAL)
9040 REN* D9* WILL HOLD SYSDATE IN MH/DD/YY FORMAT
9050 REH* ****************
9060 FOR X=51 218 TO 51225
9070 LET D9*=D9*+CHR(PEEK(X))

9080 NEXT X

Example 2. BASIC subroutine to access the system date.

valid. These eight bytes are
stored in a free area of memory
protected from BASIC. In my
system, I keep the system date
at C812H to C819H; however, it
can be put anywhere.

Once the IPL is complete,
this date is available to BASIC
programs using the PEEK com-
mand, as shown in Example 2,
or to assembly-language rou-
tines. I have found this conve-
nient; I use the system date
often in dating listings, reports
and as the current date in my
biorhythm program.

Changes

The program listing is as-
sembled to run at location
4C00H, well above my BASIC. It
can be reassembled to run at
any location where you have

32FH free bytes of memory. Be
sure that no program or file on
the IPL tape will load into the
same location, or SIMPL will be
wiped out when that file is load-
ed on top of it.

To save memory and work,
SIMPL makes use of four rou-
tines found in my monitor:
RDBLK, which loads a file from
tape and returns with the carry
flag set if an error is encoun-

tered; SINP, which outputs the
character in register B to the
screen; SOUT, which returns a
byte from the keyboard to regis-
ter A or a zero flag if no key was
pressed; and CRLF, which
sends a carriage return and line
feed to the screen, causing the
cursor to skip to the next line.
These routines are common
functions that can be found in
most monitors.

In lines 390 through 400 I
send a hex OB to the screen. On
any system with the Processor
Technology VDM-1 display
board, this will cause the screen
to clear. If you do not have the
VDM-1, substitute the corre-
sponding character for your
system, or if you do not know it,
you can delete these two lines
altogether.

Conclusion

Programming is certainly
less of a problem now. I can let
SIMPL do the work of loading
and linking my system. I find I
have more time to look through
Microcomputing or meditate on
the joys of structured program-
ming. Computers should be
simple— SIMPL is my contribu-
tion toward that goal.B

Program listing.

4C00

0010 *

* *

*********

4C00

0020 *

4C00

0030 *

SIMPL

4C00

0040 *

Solos Initial Multiple Program Load

4C00

0050 *

Written by

Hal Conbs ... March 25, 1978

4C00

0060 *

4C00

0070 *

* *

*4*44*4*4

4C00

0080 *

4C00

0090 ♦

SINPL will

load all programs from the IPL

4C00

0100 *

tape into nenory until a file named "END”

4C00

0110 *

found.

The "END" file is loaded so it

4C00

0120 *

should be a

dummy file.

4C00

0130 *

After all files are loaded SIMPL will link

4C00

0140 *

desired programs to the SOLOS nonitor by

4C00

0150 ♦

inserting apropriate entries in the SOLOS

4C00

0160 *

custon connand table.

4C00

0170 ♦

4C00

0180 *

4 4

4*4*44*4 4

4C00

0190 ♦

4C00

0200 *

The

i following prograns are on ny IMPL tape.

4C00

0210 *

4C00

0215 *

S.l

.M.P.L.

4C00

0220 *

PROCESSOR TECHNOLOGY CASSET EXTENDED BASIC

4C00

0230 *

PROCESSOR TECHNOLOGY ALS-8 MONITOR/ASSEHBLER

4C00

0240 *

HAL COMBS'S

HEX-ASCII MEMORY DUMPER

4C00

0245 *

DUMMY FILE

'END'

4C00

0250 *

4C00

0240 *

* *

*********

4C00

0270 *

The new

SOLOS custon commands are :

4C00

0280 *

4C00

0290 *

Command

: BA executes BASIC

4C00

0300 *

Connand

r AL executes ALS-8

4C00

0310 *

Connand

: DX executes DUMPX

4C00

0320 *

* *

*********

4C00

0330 *

4C00

0340 *

PROGRAM CONTROL SECTION

4C00

0350 *

4C00 C5

0360 SIMPL

PUSH

SAVE THE REGISTERS

4C01 D5

0370

PUSH

4C02 E5

0380

PUSH

4C03 06

0390

MVI

B ,0BH

CLEAR SCREEN

4C05 CD

0400

CALL

SOUT

SOLOS OUTPUT ROUTINE

4C08 CD

0430

CALL

USAGE

PRINT MESSAGE 1

4C0B CD

0440

CALL

MSAGE

PRINT MESSAGE 2

4C0E CD

0450

CALL

CRLF

SKIP 1 LINE

4C1 1 CD C9

0460

CALL

MSAGE

PRINT IPL 1 0 1 0

4C1 4 CD

0470 TLOOP

CALL

TLOAD

GET NEXT FILE ON TAPE

4C17 3A

0480

LDA

EFLAG

GET END-FILE FLAG

4C1 A FE

0490

CPI

0FFH

IF FLAG = HEX FF

4C1C CA

0500

LINKS

STOP TAPE LOADING

4C1F CD

0510

CALL

MSAGE

PRINT IPL1030

4C22 CD

0520

CALL

MSAGE

PRINT IPL 1040

4C25 C3

0530

JMP

TLOOP

GET NEXT FILE

4C28 CD

0540 LINKS

CALL

SLINK

LINK TO SOLOS

4C2B CD

0550

CALL

MSAGE

PRINT IPL 1090

4C2E CD

0560

CALL

SDATE

GET SYSTEM DATE

4C31 CD

0570

CALL

CRLF

SKIP 1 LINE

4C34 CD

0580

CALL

MSAGE

PRINT SYS-COMMANDS

4C37 CD

0590

CALL

CRLF

SPACE A LINE

4C3A CD

0600

CALL

MSAGE

PRINT NEU CUSTOM COMMANDS

4C3D CD

0610

CALL

CRLF

4C40 CD

0620

CALL

MSAGE

4C43 CD

0630

CALL

USAGE

4C46 CD

0640

CALL

MSAGE

4C49 El

0670 ENDIT

POP

RESTORE REGISTERS

4C4A D 1

0680

POP

4C4B Cl

0690

POP

4C4C

0700

RET

GOBACK

4C4D

0710 *

4C4D

0720 *

SUBROUTINES FOLLOW

4C4D

0730 *

4C4D

0740 4 *

4 *

********

4C4D

0750 *

TLOAD

- GETS 1

NEXT TAPE FILE INTO MEMORY

4C4D

0760 * *

* *

********

4C4D

0770 TLOAD

LXI

H.THDR

POINT TO TAPE HEADER

4C50

0780

LXI

D,0H

SET LOAD ADDR. « HEADER ADDR.

4C53

0790

MVI

A.80H

SET FOR TAPE Ml AT 1200 BAUD

4C55

0800

CALL

RDBLK

SOLOS TAPE READ ROUTINE

4C58

0810

ERROR

TAPE READ ERROR

4C5B

0820

LXI

H.THDR

POINT TO TAPE HEADER

4C5E

0830

MOV

A,H

GET FIRST LETTER OF FILE NAME

4C5F

0840

CPI

45H

IS IT "E" ?

4C61

0850

JNZ

TPMSG

NO ...

4C64

0860

INX

4C65

0870

MOV

A.M

GET NEXT LETTER

4C66

0880

CPI

4EH

IS IT "N" ?

4C68

0890

JNZ

TPMSG

NO ...

4C6B

0900

INX

4C6C

0910

MOV

A,M

GET THIRD LETTER

4C6D

0920

CPI

44H

IS IT "D* ?

4C6F

0930

JNZ

TPMSG

NO ...

4C72

0940

INX

4C73

0950

MOV

A,H

GET FOURTH LETTER

4C74

0960

CPI

00H

IS IT " ” ?

4C76

0970

JNZ

TPMSG

NO . . . THEN GO ON

4C79

0980

MVI

A.0FFH

FOUND "END" FILE

4C7B

0990

STA

EFLAG

SET END-FILE FLAG

4C7E

1000

RET

GOBACK

4C7F

1010 TPHSG

LXI

H,THSG

GET TMSG ADDRESS

4C82

1020

SHLD

MPTR

PUT IT IN MSG POINTER

4C85

1030

LXI

H, TPTR+25 CLEAR LAST 3 POS OF FILE NAME

4C88

1040

MVI

h,20H

4C8A

1050

INX

4C8B

1060

MVI

M,20H

4C8D

1070

INX

4C8E

1080

MVI

M, 20H

4C90

1090

LXI

D,TPTR+23 POINT TO FILE NAME POS IN LINE

4C93

1100 TNOVE

LXI

H, THDR

POINT TO TAPE HEADER

4C96

1110 PLOOP

MOV

A,M

MOVE FILE NAME TO LINE

4C97

1120

CPI

00H

ENDING UITH 00 HEX

4C99

1130

4C9A

1140

STAX

4C9B

1150

INX

4C9C

1160

INX

4C9D

1170

JMP

PLOOP

4CA0

1180 * 4

4 4

* * ******

4CA0

1190 *

ERROR

- TAPE READ ERROR ROUTINE

4CA0

1200 * *

* 4

********

4CA0

1210 ERROR

LXI

D,ERMSG+35 POINT TO ERROR MESSAGE FILE

FLD

4CA3

1220

CALL

TMOVE

MOVE FILE NAME TO ERR LINE

4CA6

1230

LXI

H.ERMSG

POINT TO ERROR MESSAGE

4CA9

1240

SHLD

MPTR

PUT IT IN MESSAGE POINTER

4CAC

1250

CALL

MSAGE

PRINT IPL1501

4CAF

1260

CALL

MSAGE

PRINT IPL1502

4CB2

1270

CALL

MSAGE

PRINT IPL 1503

4CB5

1280

POP

REMOVE RETURN ADDRESS

4CB6

1290

JMP

ENDIT

4CB9

1300 * *

♦ 4

********

4CB9

1310 *

SLINK

- BUILD

SOLOS LINKAGE

4CB9

1320 * *

* 4

********

4CB9

1330 SLINK

LXI

H,LDATA

POINT H-L TO LINK-DATA

4CBC

1340

LXI

D,CTBL

POINT D-E TO CUSTOM TABLE

4CBF

1350 CLOOP

MOV

A , M

4CC0

1360

CPI

0FFH

END OF CUSTOM TABLE ?

4CC2

1370

YES ... RETURN

4CC3

1380

STAX

LOAD INTO CUSTON COMMAND TABLE

4CC4

1390

INX

4CC5

1400

INX

4CC6

1410

JMP

CLOOP

Microcomputing, October 1979 1 59

4CC9 142# ***************

4CC9

1430

MSAGE

- PRINT MESSAGE ON SCREEN

4CC9

1440

* *

**********

4CC9

1450

MSA6E

LHLD

HPTR

PUT MESSAGE POINTER IN H-L

4CCC

1460

MLOOP

MOV

B,H

GET CHARACTER

4CCD

1470

CALL

SOUT

SOLOS OUTPUT ROUTINE

4CD0

1480

MOV

A,B

4CD1

1490

CPI

00H

IS IT END OF MESSAGE? (00 HEX)

4CD3

1500

MSEND

THEN GOTO MESSAGE END

4CD6

1510

INX

4CD7

1520

JMP

MLOOP

4CDA

1530

MSEND

INX

POINT TO NEXT MESSAGE

4CDB

1540

SHLD

MPTR

SAVE POINTER

4CDE

1550

CALL

CRLF

SKIP 1 LINE

4CE1

1560

RET

4CE2

1570

* *

•

• *

*********

4CE2

1580

SDATE

- GET SYSTEM DATE

4CE2

1590

* *

» *

*********

4CE2

1600

SDATE

CALL

MSAGE

ASK FOR SYSTEM DATE

4CES

1610

LHLD

DPTR

GET SDATE POINTER IN H-L

4CE8

1620

MV1

C,8

MAX CHARACTERS ACCEPTED

4CEA

1630

SLOOP

CALL

SINP

SOLOS KEYBOARD INPUT

4CED

1640

SLOOP

WAIT FOR INPUT

4CF0

1650

MOV

B,A

PUT CHARACTER IN REG. B

4CF1

1660

MOV

H,B

STORE IT

4CF2

1670

CALL

SOUT

SOLOS OUTPUT ROUTINE

4CF5

1680

DCR

4CF6

1690

LAST ONE?

4CF7

1700

INX

4CF8

1710

JMP

SLOOP

4CFB

1720

* *

•

♦

• +

*********

4CFB

1730

DATA AREAS

4CFB

1740

* *

* 6

*********

4CFB

1750

CRLF

EQU

0C2F9H

SOLOS CARRIAGE RETURN i LINE FEED

4CFB

1760

THDR

EQU

0C81CH

SOLOS TAPE HEADER

4CFB

1770

CTRL

EQU

0C83CH

SOLOS CUST TABLE

4CFB

1775

SINP

EQU

0C01FH

SOLOS KEYBOARD INPUT

4CFB

1780

SOUT

EOU

0C019H

SOLOS SCREEN OUTPUT

4CFB

1785

RDBLK

EQU

0C013H

SOLOS TAPE READ

4CFB

1790

EFLAG

00H

END-FILE FLAG

4CFC

1800

HPTR

MESSAGE

HESSA6E POINTER

4CFE

1810

DPTR

0C812H

SYSDATE POINTER

4D00

1820

LDATA

EQU

SOLOS LINKAGE DATA TABLE

4D00

1830

ASC

“AL"

ALS8 CUSTOM NAME

4D02

1840

0E060H

ALS8 LINKAGE ADDRESS

4D04

1850

ASC

"BA"

BASIC CUSTOM NAME

4D06

1860

0000H

BASIC LINKAGE ADDRESS

4D08

1870

ASC

"DX"

DUHPX CUSTOM NAME

4D0A

1880

0C900H

DUMPX LINKAGE ADDRESS

4D0C

1890

0FFH

END OF LINKAGE TABLE

4D0D

1900

MESSAGE EQU

♦ *

* MESSAGE TEXT AREA * *

4D0D

1910

ASC

S.I.M.P.L."

4D22

1920

00H

4D23

1930

ASC

"Solos Initial Multiple Progran Load"

4D46

1940

00H

4D47

1950

ASC

"IPL1010

IPL NOU IN PROGRESS-

4D67

1960

00H

4D68

1970

TMSG

ASC

"IPL1020

SUCCESSFUL PROGRAM LOAD"

4D89

1980

00 H

4D8A

1990

TPTR

ASC

"IPL1030

FILE NAME :

4DA6

2000

00H

4DA7

2010

ASC

"IPL1080

SOLOS LINKAGE COMPLETE"

4DC7

2020

00H

4DEE

4DEF

ASC "IPL1090 ENTER SYSTEM DATE (MM/DD/YY)"

DB 00H

ASC "IPL1099 SYSTEM IPL NOU COMPLETE"

4E10 00

4E1 1 53

4E27 00

4E28 41

4E57 00

4E58 42

4E89 00

4E8A 44

<52

< 3A

]49

*44

4EBF 00

4EC0

4EC0 49

4EE9 00

4EEA 49

4F0B 00

4F0C 49

4F2D 00

2 060 DB 00H

2070 ASC "SYSTEM CUSTOM COMMANDS"

2080 DB 00H

2090 ASC "AL : MILL EXECUTE ALS-0 ASSEMBLER

2if0 Dg 2t\\

2110 ASC "BA : UILL EXECUTE BASIC INTERPRETER

2120 DB 00H

2130 ASC "DX ADDR1 ADDR2 : UILL DUMP MEMORY IN HEX ASCII FORM

2140 DB 00H

2150 ERMSG EQU %

2160 ASC "IPL1501 TAPE READ ERROR - FILE :

2170 DB 00N

2180 ASC "IPL1503 * * * IPL ABORTED * ♦ *"

2191 DB 00H

2200 ASC "IPL 1505 REUIND TAPE I RETRY IPL"

2210 DB 00H

CLOOP

4CBF

1410

CRLF

C2F9

0450

0570 0590 0610

1550

CTBL

C83C

1340

DPTR

4CFE

1610

EFLAG

4CFB

0480

0990

ENDIT

4C49

1290

ERMSG

4ECI

1210

1230

ERROR

4CA0

0810

LDATA

4D00

1330

LINKS

4C28

0500

MESSA

4D0D

1800

MLOOP

4CCC

1520

MPTR

4CFC

1020

1240 1450 1540

MSAGE

4CC9

0430

0440 0460 0510

0520 0550 0580 0600 0620 0630 0640

1250

1260 1270 1600

MSEND

4CDA

1500

PLOOP

4C96

1170

RDBLK

C01 3

0800

SDATE

4CE2

0560

SIMPL

4C00

SINP

C01F

1630

SLINK

4CB9

0540

SLOOP

4CEA

1640

1710

SOUT

C01 9

0400

1470 1670

THDR

C81C

0770

0820 1100

TLOAD

4C4D

0470

TLOOP

4C14

0530

THOVE

4C93

1220

TMSG

4D68

1010

TPMSG

4C7F

0850

0890 0930 0970

TPTR

4D8A

1030

1090

160

Microcomputing, October 1979

means documented software.

Shopping for business software? Looking for thoroughly tested, reliable programs with complete source
listings? You’re looking for documented software - and you just found it.

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If you are a dealer you can buy the source programs on disk as listed in each book for $250.00 per title.
There are no copying restrictions - no royalties for subsequent copies. We copyright only the printed
word. Since OSBORNE prefers to publish books rather than customize programs, we refer all end users to
their nearest OSBORNE dealer. Dealers who buy a disk from us are entered on our dealer referral list.

Can’t use CBASIC? Many independent consultants have successfully converted the programs to run on
almost every microcomputer available today, using the OSBORNE/McGraw-Hill books as the primary
documentation. Call or write for a complete list of these conversions. Our books are also available in Wang
BASIC.

I Order Form

Title

Price

Quantity

Amount

22-5 Payroll with Cost Accounting - CBASIC

$15.00

23-3 Accounts Payable/ Receivable- CBASIC

15.00

24-1 General Ledger - CBASIC

15.00

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iS Reader Service— see page 227

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^06 I

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(415) 548-2805 *TWX 910-366-7277 I ill

SI 055

Microcomputing, October 1979 161

Ken Klosson

4040 E. Piedmont Space 71
Highland CA 92346

“ay.” Hence, “scram” becomes
“amscray” and “nix” becomes
“ixnay.”

Pig Latin

Maybe you could use this for program protection.

5 REM LIST VOWELS AND ENDING CHARACTERS
10 FOR 1=1 TO 5: READ V$(I): NEXT
20 DATA A,E,I,0,U

30 FOR 1=1 TO 5: READ EC$(I): NEXT
4 0 DATA M . " M • *' ” 7 M •* « »» »» »»

50 DIM L$(100) : DIm’pI(IOO): W3$ = "AY": CR$ = "jT
60 TW= 23 : REM ADJUST TO YOUR TERMINAL WIDTH

70 PRINT: PRINT: PRINT: PRINT: PRINT

71 PRINT TAB ( 6 ) ; "AUTOMATED”

72 PRINT

73 PRINT TAB( 7 ) ; "LANGUAGE”

74 PRINT

75 PRINT TAB( 5 ) ; "TRANSLATION"

7 6 PRINT : PRINT : PRINT : PRINT : PRINT : PRINT : PRINT

77 PRINT TAB( 6 ) ; "PIG LATIN"

78 PRINT: PRINT

79 PRINT "ENTER LINE TO BE TRANSLATED:"

80 PRINT: PRINT

99 REM GET INPUT

100 LC=-1: BW=1 : INPUT L$

105 REM READY FOR FULL TEXT?

110 IF L$="/" OR L$="?" THEN 1000

115 REM CRLF

120 P$(N)=CR$: N=N+1

125 REM TAKE L$ ONE CHARACTER AT A TIME
130 FOR A=1 TO LEN ( L$ )

140 L1$=MID$(L$,A,1)

145 REM FIND FIRST VOWEL AND ENDING CHARACTER
150 FOR B= 1 TO 5

160 IF Ll$ <>EC$ ( B) OR BW <> A THEN 165

161 BW= BW+1 : P$(N-1)=P$CN-1)+L1$: GOTO 210
165 IF LC<> -1 THEN 180

170 IF L1$=V$ ( B) THEN LC=A-BW

175 IF L1$="Y" AND A > BW THEN LC=A-BW

180 IF L1$=EC$ (B) THEN EW=A: V74$ = EC$(B): GOTO 500

190 NEXT B

200 IF A=LEN(L$ ) THEN EW=A+1: W4$=EC$(5): GOTO 500
210 NEXT A

220 PRINT: PRINT: PRINT: GOTO 100

499 REM TRANSLATE AND PRINT EACH INPUT

500 W$=MID$(L$,BW,EW-BW)

51-0 IF LC < 1 THEN P$ (N) =W$+W3$+W4$ : GOTO 550
520 W1 $= RIGHT $ (W$ ,LEN(W$ )-LC)

530 W2$=LEFT$(W$,LC)

540 P$(N)=W1$+W2$+W3$+W4$

55 0 PRINT P $ ( N ) ;

560 N=N+1: BW=EW+1: LC=-1
570 GOTO 210

999 REM FULL TEXT TRANSLATION

1000 CC=0

1010 FOR C=1 TO N-l

1020 IF P$(C)=CR$ THEN PRINT: GOTO 1050
1030 IF CC+LEN(P$ CC ) ) > TW THEN CC = 0: PRINT
1040 PRINT P$(C);

1050 CC=CC+LEN(P$(C) )

1060 NEXT C

1070 IF L$="/" THEN 1090
1080 PRINT: GOTO 100
1090 END

Program listing.

H ere is the world’s first full-
function language-trans-
lation program ever to be
released to the public domain
in 8K BASIC! With this power-
ful, albeit porcine, program you
can select almost any text for
translation: insurance policies,
nursery rhymes, Joyce’s Ulysses,
names of organic chemicals,
lyrics to rock ballads, program-
ming tutorials . . . whatever!
Your mighty micro will study,
labor and haltingly print out a
faithful translation of your text
in pure ASCII Pig Latin.

Pig Latin is normally asso-
ciated with the English lan-
guage. However, in what may
be a linguistic milestone, this
program will pig-latinize any
language that can be written
with the ASCII character set. A
text may even be input in Pig
Latin. In that case, the transla-
tion will be rendered in (Pig
Latin) 2 .

For the uninitiated, Pig Latin
is a “language” used by older
people who don’t want to be
understood by younger people.
It is a sort of secret language.
But the security on this secret
is so miserable that the “older”
people may be only six or seven
years of age. Nevertheless, Pig
Latin continues to be passed
along from generation to gener-
ation.

In the absence of a national
academy to guard the purity of
Pig Latin, some minor varia-
tions do exist. It is generally
agreed, however, that the prin-
cipal syntactical principle
(Whew! Hereinafter called the
PSP) is to move any consonants
at the beginning of a word to
the end of that word and add

BASIC Bacon

Beyond the PSP the rules
seem rather loose. Lacking a
HANG LOOSE mode in my
BASIC interpreter, I was forced
to establish a few reasonable
rules:

1. Every word gets pig-latin-
ized. (Some users exempt ar-
ticles and other short words.)

2. Words beginning with
vowels are translated simply by
adding “ay.”

3. “Y” is sometimes a vowel.
Whether “y” is or is not a vowel
is a matter of pronunciation, a
skill most micros do not pos-
sess. The following rules work
well enough.

A. A “y” that is the first letter
of a word will be considered a
consonant. This is fine for “you,”
“yes” and “yogurt.” I will apolo-
gize to “Ypsilanti” but let us try
to accept the adverse effect on
“yttrium.”

B. A “y” after the first letter
of a word will be considered a
vowel. This ensures the deluxe
treatment for “by,” “sly,” “try,”
as well as “byte” and “Styx.”

Pearls (i.e., Strings)

Before Swine

The program is written in Mi-
crosoft 8K BASIC (OSI 6502 ver-
sion) and should be directly
loadable in many systems. Nat-
urally, it depends on string
functions. If you haven’t had
much use for these, or if you are
adapting the program to other
BASICS, it may help to know:
LEN(A$) returns the length of
string A$ in characters; LEFTS
(A$,l) returns I characters be-
ginning at the left of AS; RIGHTS
(AS, I) returns the last I charac-
ters at the right of AS; MID$(A$,
l,J) returns a sub-string begin-
ning at the Ith character and
continuing right for a total of J
characters.

Running the program is sim-
ple. After the title there is a re-
quest for input. After each input
there is an immediate transla-
tion followed by a request for
more input. When the entire
text has been entered, a sepa-
rate input of either “?” or
will produce a printing of all Pig

1 62 Microcomputing, October 1979

Strings

V$(X) A list of vowels (except y)

EC$(X) A list of characters that end words

L$ A /ine of input

LI $ A single character from L$

P$(X) The list of Pig Latin words
CR$ A flag in P$(X) used to output a CPFL
W$ A word extracted from L$ before translation
W1$ Remainder of W$ after left consonants are removed
W2$ The left consonants of W$

W3$ “AY”

W4$ The character that ended W$

Numerics

A,B,C,I Loop counters

LC The number of Left Consonants

BW Nth character of L$ that begins the current word

EW Nth character of L$ that ends the current word

N Number of next word to be stored in P$(N)

CC Count of Characters printed on current line

TW Terminal Width

Table 1. Variable assignments.

W1$+ W2$+ W3$ + W4$

ig p ay (space)

Fig. 1.

Latin text from the current run
without intervening English. If
“?” is entered, additional input
will be requested. On the
program ends.

The program accepts a
series of words as input. Pig
Latin, however, operates on in-
dividual words. So the program
must isolate the separate
words (by looking for ending
characters, either a space or
certain punctuation).

Also, the word must be exam-
ined for consonants on the left
end. We do this by looking for
vowels since there are fewer to
look for. We call the word W$,
the left consonants W2$, the
rest of the word W1$; the “ay”
(from the PCP) is W3$, and the
ending character is W4$. When
W1$ through W4$ are assem-
bled in numerical order, we
have the translation. For the
word “pig,” see Fig. 1. Atthay
isay igpay atinlay.

If the word begins with a
vowel, the word itself, W$, re-
places W1$ and W2$ in accor-
dance with reasonable rule
number two. This process was
rigged so that the same proce-
dure would apply if a “word”
with no vowels was input.

The key to this process is the
use of the variable LC (left con-
sonants), which is set to -1
before each word is translated.
If a word arrived at line 500 for
translation and printing, and LC
= -1, no vowels were found.

If LC = 0, the first letter is a
vowel. In either case, no attempt
is made to find W1$ or W2$.
LC = - 1 is also the flag that
stops the search for vowels
once one has been found (see
line 165).

The variable assignments
are intended to be mnemonic in
the hope that little explanation
will be necessary. There are,
however, a couple of spots that
warrant some help.

Note that the decision to
start translation and printing is
made in line 180 when an ending
character is found. If none is
found the word will never be
translated. This can occur if the
last character in an input is a
letter. Line 200 saves that word
by supplying an ending charac-
ter.

No POKES in This Pig

Line 160 is, frankly, a patch.
Consider the word “yes!!!” Up
to the first exclamation, every-
thing is fine. The second and
third exclamation points begin
and end words all by them-
selves. It comes out “esyay!ay!
ay!” Line 160 retroactively adds
these ending characters to the
end of the preceding word and
starts the current word one
character later. Since the pre-
ceding word has already been
printed, the results are not vis-
ible until the final printing.

In line 50, TW (terminal width)
is set to 23. (Yep, that’s my ter-

minal width!) Change TW to
equal the terminal width of your
system.

There is a small amount of
formatting in the final printing
(beginning at line 1000). In line
120, CR$ (CRLF flag) is inserted
into the Pig Latin word list P$(N)
at the beginning of each input
to keep the input lines sepa-
rated. Line 1030 also checks to
see if there is enough terminal
width left before printing each
word. If not, it prints a CRLF to
avoid awkward word splitting

at the right of the screen.

Although this program is
short and can be loaded quickly,
it runs rather slowly. This adds
to the fun. It appears that your
mighty micro is really sweating
at last. Naturally, your input
should omit commas and colons
(they are too much for BASIC).
Quotes should also be left out.
They show up all over the place.
(Cleaning that mess up was too
much for me.) Try to input Baa
Baa Black Sheep. The results
are eirdway.B

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arl Egetter

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tinyFORTH

tinyFORTH is the TRS-80 cassette oriented
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tinyFORTH includes these features:
Dictionary-oriented structured high-level
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Specify TRS-80 level when ordering.

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Box 2304 Dept. A3 Boston, VA. 22090

Reader Service— see page 227

Microcomputing, October 1979 1 63

Bela is’ Master Index to Computer Programs
in BASIC Gives You Access to $14,836.14
Worth of Computer Programs for Just $7.95!

Now Available Off-The-Shelf *^F2i

You paid hundreds or even thousands of dollars
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But computer programs cost money. In a recent
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Belais' Master Index gives reviews of 531 pro-
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This large 8 1/2 x 11. 192-page directory is
packed with information This is not just a simple
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Each BMI review is complete— it has everything
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Source information shows you where the program
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We don't provide the program listings them-
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You don't have to be a programming wizard to
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To order, write your name, address, and the
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Custom Fabric Dust Covers made from velour, cor-
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TERMS: PREPAID. Check, Money-order, Master
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MINI FLOPPY DISK DRIVES
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2 Drive cable $25.00 4 Drive cable $35.00

THE ELECTRIC PHONE II

Turn your TRS-80 into an automatic phone dialer with this
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Tape version $14.95 Disk version $19.95

REAL TIME GAMES PACKAGE

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Both of the above on cassette for level 2, 1 6k. $1 4.95

EXPANDED MAILLIST

By Harry Hopkins

Utilizes sequential files for rapid access in sorting into labels or
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Maillist program on diskette with manual $59.95

Send for free catalog.

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1 64 Microcomputing, October 1979

TRS— 80

FORTRAN

Why waste time and effort porgramming (*>
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Microsoft's Regular Price $350

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Discount Price $280

(a 20 % discount)

SUPERMAIL

This machine code program, written and
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For half the price of the TRS-80 Fortran
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RS— 232

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A superior design in RS-232 Printer Inter-
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Reader Service— see page 227

Microcomputing, October 1979 165

WELCOME TO THE GAME OF ' TOUCH '

IF THE LINE ABOVE APPEARS SHARP & CLEAR r YOU ARE NOT YET READY TO PLAY.

(I.E. GO HAVE ANOTHER DRINK)

IF YOU ARE INDEED READY r YOU PROBABLY WON'T MIND GOING TO GATHER MORE PLAYERS.
AN EQUAL MIX OF MALES & FEMALES IS DESIRABLE (AT MOST PARTIES).

ENTER A 'CR' WHEN READY TO CONTINUE :

move on someone else at the
party or simply can’t get out of
the room. Unfortunately, only
two or three of the people in the
room could actually get involved
in most of the computer games
at one time. That is, until Touch
made its debut.

THIS GAME GETS PEOPLE TO TOUCH EACH OTHER. PEOPLE ACTUALLY LIKE TO TOUCH AND
BE TOUCHED. UNFORTUNATELY OUR SOCIETY PUTS SOCIAL CONSTRAINTS ON PHYSICAL
CONTACT. IN HONOR OF SOCIAL NORMS WE DUTIFULLY MAINTAIN OUR 'PERSONAL SPACES'.

WELL I DIRECT THIS GAME » AND I HAVE NO SOCIAL CONSCIENCE !

I WILL DIRECT EACH OF YOU, IN TURN, TO TOUCH ANOTHER PERSON IN A PARTICULAR WAY
(PUT THE BLAME ON ME). YOU WILL HAVE APPROX. 5 SECONDS TO MAKE EACH CONTACT.
YOU THEN HOLD EACH OF YOUR PERSONAL CONTACTS UNTIL A NEW 'TOUCH' COMMAND
SUPERCEDES A PREVIOUS ONE.

THE FIRST PAIR TO 'BREAK' OR 'REFUSE' A CONTACT LOSES (YOU CHOOSE THE PENALTY).
TO MOMENTARILY INTERUPT A GAME , TYPE A ' CTL-B ' f TO END* TYPE A 'CTL-C'

ENTER A 'CR' WHEN READY TO CONTINUE J

HOW MANY MALES IN THE GROUP ? 3

HOW MANY FEMALES IN THE GROUP ? 3

NAME OF MALE NBR 1 ? TOM

NAME OF MALE NBR 2 ? BOB

NAME OF MALE NBR 3 ? TED

NAME OF FEMALE NBR 1 ? SHIRLEY

NAME OF FEMALE NBR 2 ? CAROL

NAME OF FEMALE NBR 3 ? ALICE

Adrian R. Thornton
6404 Overton Road
Louisville KY 40228

ENTER A 'CR' WHEN READY TO CONTINUE .*

*** TED ***

PLACE YOUR REAR END ON ALICE 'S RIGHT KNEE

*** CAROL ***

PLACE YOUR RIGHT FOOT ON TED 'S RIGHT THIGH
*** BOB ***

PLACE YOUR RIGHT THIGH ON ALICE 'S LEFT EAR
*** ALICE ***

PLACE YOUR LEFT FOREARM ON TOM 'S CHIN
BOB

PLACE YOUR RIGHT HAND ON CAROL 'S CHEST

*** CAROL ***

PLACE YOUR LEFT EAR ON BOB 'S LEFT THIGH

M y wife and I throw a couple
of good-sized parties each
year. On those occasions, our
block becomes a parking lot; the
kitchen, a bar; the living room, a
dance floor; the bathrooms, a
blur of activity; and the “com-
puter room,’’ a midway. The

The Game

The following program,
Touch, can involve the people in
the computer room, the living
room, the kitchen and the bath-
rooms, all at one time. Although
as few as two people may play,
the larger the number of partici-
pants, the more fun is the game.

Touch is a social game. The
premise upon which it is based
is that people like to touch and
be touched by other people, and
if it weren’t for our social inhibi-
tions (and the need to make a liv-
ing), we might spend all our wak-
ing hours groping at each other.
To overcome these social con-
straints we resort to liquor,
dope, prostitution, and some
even go so far as to get married.

Now Touch, combined with a
moderate amount of alcohol,
provides yet another, and more
socially acceptable way of sur-
mounting our social inhibitions.
The computer decides which of
the participants shall touch, and

*** BOB ***

PLACE YOUR FOREHEAD ON SHIRLEY 'S RIGHT KNEE
*** ALICE ***

PLACE YOUR REAR END ON TED 'S RIGHT SHOULDER

Sample run.

computer room usually con-
tains a large enough crowd to
make the fire marshall cringe;
however, most of the people in
there are either waiting in line
for the computer, making a

in what manner they shall touch
each other. When the computer
issues the touch command, the
participants do not have to feel
responsible for breaching each
other’s personal space; after all,

166 Microcomputing, October 1979

the computer made them do it!
Touch provides a game-like at-
mosphere where the partici-
pants can relax and enjoy the
feelings of personal contact
they would normally feel re-
stricted from enjoying.

The Program

The program is relatively sim-
ple. It runs sequentially through
the following four steps:

1. Print game directions

2. Load the applicable body
parts

3. Get all participants’ names

4. Begin printing touch com-
mands

Step four is an infinite loop,
interruptible via CTL-B. This
touch command loop alternate-
ly selects a male; then a female
name randomly from the partici-
pant list M$. This selected par-
ticipant is then directed to touch
a randomly selected body part
of his/hers to a randomly select-
ed body part of a randomly
selected participant of the op-
posite sex. There is a pause of
about five seconds, during
which the above pair of partici-
pants must attempt to complete
the directed contact. They must
maintain this contact until a
later touch command super-
cedes this one, or until a pair of
players breaks or refuses a con-
tact, thus losing the game.

The above touch commands
will continue to be issued until
someone decides to temporarily
halt the loop via CTL-B. When
everyone is ready to begin
again, a carriage return is
entered, and the touch com-
mand loop continues from
where it was interrupted.

The result is an uproarious
mass of people frantically trying
to satisfy and keep up with the
computer’s sometimes impossi-
ble touch commands. The game
soon becomes as much fun to
watch as it is to participate in.

Modifications

The program is easily
modifiable to make it accept-
able to a range of participants
from your church group to the
local swingers’ club. The intro-
duction given by the program is
geared toward a party well
under way. You may want to
slant the introduction to a dif-

ferent type of group. The list of
applicable body parts may also
be altered. Simply change the
data statements to reflect the
level of intimacy you desire.
Also reset the variable N1 in line
number 290 to the current num-

ber of body parts defined by the
data statements.

Touch was written on a
Heathkit H8 using Extended
Benton Harbor disk BASIC. The
program coding is also compati-
ble with the Heath Extended

cassette BASIC. The printing of
the introduction has been de-
signed for the 12-line H9 CRT.
You may want to change the
screen holds (GOSUB 890) to be
compatible with your terminal
type. ■

oooio

00020

00030

00040

00050

00060

00070

00080

00090

00100

00110

00120

00130

00140

00150

00160

00170

00180

00190

00200

00210

00220

00230

00240

00250

00260

00270

00280

00290

00300

00310

00320

00330

00340

00350

00360

00370

00380

00390

00400

00410

00420

00430

00440

00450

00460

00470

00480

00490

00500

00510

00520

00530

00540

00550

00560

00570

00580

00590

00600

00610

00620

00630

REM

«< TOUCH »>

< BY ADRIAN R. THORNTON* APRIL 1*

1979 >

PRINT J PR I NT ! PRINT TAB< 15) * 'WELCOME TO THE GAME OF 'TOUCH' '

PRINT 'IF THE LINE ABOVE APPEARS SHARP & CLEAR* YOU ARE NOT YET READY TO PLAY.'

PRINT TAB< 15) * * ( I .E. GO HAVE ANOTHER DRINK)"

PAUSE 3000
PRINT i PRINT

IF YOU ARE INDEED READY* YOU PROBABLY WON'T MIND GOING TO GATHER MORE PLAYERS.
AN EQUAL MIX OF MALES & FEMALES IS DESIRABLE (AT MOST PARTIES).'

GOSUB 890
PRINT

THIS GAME GETS PEOPLE TO TOUCH EACH OTHER. PEOPLE ACTUALLY LIKE TO TOUCH AND'
BE TOUCHED. UNFORTUNATELY OUR SOCIETY PUTS SOCIAL CONSTRAINTS ON PHYSICAL'
CONTACT. IN HONOR OF SOCIAL NORMS WE DUTIFULLY MAINTAIN OUR 'PERSONAL SPACES'

WELL I DIRECT THIS GAME* AND I HAVE NO SOCIAL CONSCIENCE • ■

I WILL DIRECT EACH OF YOU* IN TURN* TO TOUCH ANOTHER PERSON IN A PARTICULAR WAY'
PRINT '(PUT THE BLAME ON ME). YOU WILL HAVE APPROX. 5 SECONDS TO MAKE EACH CONTACT.'
PRINT 'YOU THEN HOLD EACH OF YOUR PERSONAL CONTACTS UNTIL A NEW 'TOUCH' COMMAND*
SUPERCEDES A PREVIOUS ONE.'

THE FIRST PAIR TO 'BREAK' OR 'REFUSE' A CONTACT LOSES (YOU CHOOSE THE PENALTY).'
TO MOMENTARILY INTERUPT A GAME, TYPE A 'CTL-B'* TO END* TYPE A 'CTL-C'*

PRINT
PRINT
PRINT
GOSUB 890

REM

REM FOLLOWING IS THE LIST OF BODY PARTS (RATED PG)

N1=29.REM NUMBER OF BODY PARTS* BELOW

DATA "RIGHT FOOT'* 'LEFT FOOT'* 'RIGHT HAND'* 'LEFT HAND'

DATA 'RIGHT KNEE'* 'LEFT KNEE'* 'RIGHT ELBOW'* 'LEFT ELBOW
DATA 'RIGHT SHOULDER' * 'LEFT SHOULDER '*' RIGHT HIP'* 'LEFT HIP'
DATA 'RIGHT THIGH'* 'LEFT THIGH '*' RIGHT CALF'* 'LEFT CALF*

DATA 'RIGHT FOREARM '*' LEFT FOREARM '*' RIGHT EAR'* 'LEFT EAR '
DATA 'WAIST' * 'NOSE' , 'BACK' * 'CHEST' * 'BELLY BUTTON '*' LIPS '

DATA 'FOREHEAD'* 'CHIN'* 'REAR END'

DIM B$(N1 ) *N(2)

FOR 1=0 TO Nl-1 J REM LOAD BODY PARTS
READ B$ ( I )

NEXT I

PRINT ♦* PRINT * CNTRL 0*890JREM SET CTL-B EXIT

REM

INPUT 'HOW MANY MALES IN THE GROUP ? **N(1)

INPUT 'HOW MANY FEMALES IN THE GROUP ? **N(2)

IF N( 1 )>0 AND N(2>>0 THEN 500

PRINT 'SORRY* NEED AT LEAST ONE OF EACH SEX'IGOTO 440
IF ABS(N(1)-N(2))/MAX(N(1)*N(2)X.25 THEN 530
IF N ( 1 ) <N ( 2 ) THEN PRINT 'COULDN'T FIND ANY MORE GUYS* HUH ?
PRINT 'COULDN'T FIND ANY MORE GIRLS HUH ? TOO BAD.'

REM GET NAMES OF PARTICIPANTS
DIM M*(2,MAX(N(1)*N(2)))*T$(2)

T$(1)='MALE' »T$(2)=' FEMALE '

FOR K=1 TO 2
PRINT

FOR 1=1 TO N(K)

PRINT 'NAME OF 'JT$(K>*' NBR 'III' ' *

LINE INPUT * M$ ( K * I )

M$(K*I)=M*(K,I>+ ' '

TOO BAD.': GOTO 530

00640 REM CHECK FOR DUPLICATE NAMES

00650 FOR J=0 TO 1-1

00660 IF M$ ( K» I ) <>M$ (K * J) THEN 700

00670 PRINT 'THERE IS MORE THAN ONE ' *Mt (K, I )

00680 M$(K*I)=M$(K*I)+STR$(I) JJ=I-1

00690 PRINT T$(K) » ' NBR ' * STR$ ( I > * ' WILL BE IDENTIFIED AS ' • * M$ ( K * I ) * ■ ' ■

00700 NEXT J

00710 NEXT I

00720 NEXT K

00730 :

00740 PRINT 1PRINT t GOSUB 890

00750 FOR 1=1 TO 12:PRINT JNEXT IJREM CLEAR H-9 CRT

00760 REM

00770 T=2

00780 REM THE FOLLOWING IS THE TOUCH DIRECTOR ROUTINE
00790 T=ABS(T-3) .*REM FLIP-FLOP

00800 REM FOLLOWING IS COMMAND TO THE 'TOUCHER'

00810 PRINT '*** '*M$(T*INT( RND (1)#N(T))+1)*' ***•

00820 PAUSE 750

00830 REM FOLLOWING IS WHERE & WITH WHAT THE 'TOUCHER' IS TO TOUCH THE 'TOUCHEE'

00840 PRINT 'PLACE YOUR ' * B$ ( INT ( RND ( 1 ) *N1 ) ) * ' ON ' * M$ ( ABS ( T-3 ) * INT ( RND ( 1 ) *N ( ABS ( T-3 ) ) ) +1 ) *
00850 PRINT "S ' *B$( INT (RND( 1 )*N1 ) )

00860 PAUSE 3000J PRINT :GOTO 790

00870 REM

00880 REM CTL-B INTERUPT/SCREEN HOLD SUBROUTINE

00890 LINE INPUT ' ENTER A 'CR' WHEN READY TO CONTINUE : '?Ci

00900 RETURN

Program listing.

Microcomputing, October 1979 1 67

MAGIC WAND

Word Processing System

the most powerful, most flexible word
processing software ever written for a
CP/M*-based computer.

We could spend our entire time
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package.

Don’t get us wrong. We have cre-
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But that’s only half the story.

The other half is what we do for the
user. We have written our user’s man-
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stand even if you don’t have a Ph.D. in
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The manual includes a step-by-
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system disk so that you get hands-
on experience while you learn.

For everyday use there is a handy
reference card with a thumbnail de-
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key functions.

In short, we’ve done everything we
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THE STATE OF THE ART HAS CHANGED.

V* S92

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CHECKS IN MICRO-
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Wondering how to use your micro to print checks for personal
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RADIO SHACK TRS-80 HEATH H-8

JOGATHON 80/8

THE PROGRAM FOR

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USER GROUPS RECOGNIZE NEED/POTENTIAL

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TRS-80 OR H-8 WILL HANDLE 10,000 PLEDGES
The Jogathon 80/8 system operating with a Heath H-8 w/dual
disks and 40K memory or the TRS-80 w/dual disks and 32K
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DESIGNED FOR WIDE RANGE OF PRINTERS

Printed outputs from Jogathon 80/8 include bills, detailed re-
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1 68 Microcomputing, October 1979

TBS -80 TRS-80 TRS-80 TRS-80 TRS-80 TRS-80 TRS-80 TRS-80 TRS-80

Word Processing

Complete word processing with the
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Featuring:

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• The electric pencil

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Microcomputing, October 1979 1 69

Bob Bosen
Box 93

Magna UT 84044

Program Debugging:
the Yellow-Brick-Road Approach

Programs sometimes misbehave. Return them to the right path with this program.

0038

0008

0038

C 5

0010

0039

0020

003A

0030

003B

0035

003E

0040

0050

0043

0060

0045

0070

0048

0080

004B

0090

004E

0095

0051

0100

0053

0110

0056

0120

0058

0130

005B

0140

005C

0145

005D

0150

005E

0160

0061

0170

0062

0180

0063

0190

0066

0200

0069

0210

006B

0220

006E

0230

0070

0240

0073

D 1

0250

0074

0260

0075

0270

0076

0280

0079

0290

007A

0300

007B

0310

007E

0315

0081

0320

0083

0330

0086

0340

0088

0350

008B

0360

008C

C j

0370

008D

0380

008E

0390

0091

0400

0092

0410

0093

0420

0096

0430

0099

0432

009B

0434

009E

0436

00A0

0438

OOA3

0440

00A4

0450

00A5

0460

00A6

0470

00A9

0480

00AA

0490

00AB

0500

00AE

0900

00B1

1000

00B1

1010

TTYOUT EQU 0F09BH
PUSH B
PUSH D
PUSH H
STA TEMPI
MV I B,'A'
CALL TTYOUT
MV I B,' '
CALL TTYOUT
LDA TEMP 1
CALL 0F1D3H
CALL CRLF
MVI B, 'H'
CALL TTYOUT
MVI B, ' '
CALL TTYOUT
POP H
PUSH H
MOV A,H
CALL 0F1D3H
POP H
MOV A,L
CALL 0F1D3H
CALL CRLF
MVI B,'D'
CALL TTYOUT
MVI B,' '
CALL TTYOUT
POP D
PUSH D
MOV A f B
CALL 0F1D3H
POP D
MOV A,E
CALL 0F1D3H
CALL CRLF
MVI B,'B'
CALL TTYOUT
MVI B,' '
CALL TTYOUT
POP B
PUSH B
MOV A,B
CALL 0F1D3H
POP B
MOV A,C
CALL 0F1D3H
CALL CRLF
MVI B,'S'
CALL TTYOUT
MVI B, ' '
CALL TTYOUT
POP H
PUSH H
MOV A,H
CALL OF1B3H
POP H
MOV A,L
CALL 0F1D3H
STOP JMP STOP

CRLF EQU 0F0A6H

TEMPI EQU 0F3F0H

PRINT REG. B *
SAVE REGISTERS

ASCII SPACE

GET A *

PRINT A (HEX) *

PRINT CRLF *

ASCII H

ASCII SPACE

RESTORE H

SAVE L

GET H IN A

PRINT IT *

RESTORE L

GET L IN A

PRINT IT *

PRINT CRLF *

ASCII D

ASCII SPACE

RESTORE D

SAVE E

GET D IN A

PRINT IT *

RESTORE E

GET E IN A

PRINT IT *

PRINT CRLF *

ASCII B

ASCII SPACE

RESTORE B

SAVE C

GET B IN A

PRINT IT *

RESTORE C

GET C IN A

PRINT IT *

PRINT CRLF *

ASCII S

ASCII SPACE

GET STACK IN HL
SAVE L
GET H IN A
PRINT MSB OF STACK*
RESTORE STACK TO H
GET L IN A
PRINT IT *

FINISHED! LOOP HERE
PRINTS CR, LF ♦
SAVE A BYTE HERE *

Listing 1. This routine prints the contents of all 8080 registers
at the moment of entry. It uses three external subroutine calls:
CRLF must print a carriage return and line feed, TTYOUT must
print the contents of the B register in ASCII and 0F1D3H must
print the contents of A as two ASCII hex bytes. Listing 2 will
work for 0F1D3H. Lines ending with an asterisk may need minor
changes from one system to another.

M y computer used to ride
frequent tornadoes into
Munchkin land. I can always
tell when this happens because
the front panel lights start
flashing as though they’ve just
been “hexed” by the Wicked
Witch of the West, and my ter-
minal acts like acrystafball with
a short circuit.

If you’ve never had a program
push your 8080 over the rain-
bow, to act as if it’s doing ToTos
rather than GoTos, or a hard-
ware problem that made your
programs “bomb,” then you

can skip this article. But if you
occasionally find your assem-
bly-language programs lost
somewhere in the land of Oz,
then you’ll find lots of uses for
a routine that will tell you how
you got there.

Program Applications

Listing 1 is a “trap” routine
that will print the contents of all
of the 8080 registers at the mo-
ment of entry. In addition, the
contents of the top of the stack
are printed. I have found it very
useful in debugging a program

0000

♦THIS PROGRAM

CONVERTS REGISTER

0000

0001

*"A" GO ASCII

HEXADECIMAL

0000

0002

♦DIGITS AND PRINTS THEM. ALL

0000

0003

♦REGISTERS ARE

PRESERVED.

0000

0012

PUSH B

SAVE REGISTERS

0001

D 5

0013

PUSH D

0002

E 5

0014

PUSH H

0003

0020

STA TEMP2

SAVE BYTE *

0006

0030

ANI OFOH

GET 1ST NIBBLE

0008

0032

RAR

SHIFT TO PLACE

0009

0034

RAR

000A

0036

RAR

OOOB

0038

RAR

000C

0040

CALL CONVERT

MAKE IT ASCII

000F

0050

CALL TTYOUT

PRINT IT *

0012

0060

LDA TEMP2

GET BYTE BACK *

0015

0070

ANI 0FH

GET 2ND NIBBLE

0017

0080

CALL CONVERT

MAKE IT ASCII

001 A

0090

CALL TTYOUT

PRINT IT *

001 D

0110

POP H

RESTORE REG'S

001 E

0120

POP D

001 F

0130

POP B

0020

3 A

0140

LDA TEHP2

0023

0150

RET

THAT'S ALL!

0024

0220

♦THIS CONVERTS

THE LEAST

0024

0222

♦SIGNIFICANT NIBBLE OF "A 1 *

0024

0224

♦TO ASCII HEX

AND PUTS THE

0024

0226

♦RESULT IN "B"

0024

0250

CONVERT CPI 0AH

DIGIT OR LETTER?

0026

0260

JM NUMBER

0029

0270

SBI 9

LETTER

002B

0280

0RI 40H

002D

0290

MOV B f A

002E

0300

RET

002F

0400

NUMBER 0RI 30H

0031

0410

MOV B, A

0032

0420

RET

0033

0900

TTYOUT EQU 0F09BH

PRINT REG H B" *

0033

0910

TEMP2 EQU 0FFFEH

STORE A BYTE *

Listing 2.

This program converts the bytes in register A to2AS(

hexadecimal bytes and prints the results. This routine references
the external subroutine TTYOUT, which must print the contents
of the B register in ASCII. Lines ending with asterisks may need
minor modifications in different systems.

170 Microcomputing, October 1979

to insert jumps to this routine
at strategic points to verify the
operation of preceding
algorithms.

The routine itself occupies
121 bytes and may be assem-
bled anywhere in memory. It ex-
ecutes almost instantly and in-
terfaces with a user-provided
routine called TTYOUT, which
must print the contents of the B
register in ASCII. It makes ex-
tensive use of the stack for tem-
porary storage and uses just
one byte that cannot be ROM;
the byte labeled TEMPI has
to be located somewhere in
RAM.

The CALL 0F1D3H instruc-
tion is for owners of the Pro-
cessor Technology software

package one. This routine
prints the value in the ac-
cumulator as two ASCII hexa-
decimal characters. If you don’t
have software package one or
access to a routine to do this,
then the routine in Listing 2 will
work nicely.

A second useful application
of this “yellow-brick-road” pro-
gram is the result of certain
hardware characteristics of the
8080 microprocessor. In most
8080 memory schemes, unin-
stalled memory blocks look like
continuous bytes of hexadeci-
mal FF to the processor. This
corresponds to the RESTART 7
instruction, which amounts to
the same thing as a CALL 0038
HEX sequence.

All of this means that when-
ever the processor gets lost
and starts trying to execute
programs in uninstalled mem-
ory, it will immediately be
forced to continue execution at
0038 Hex. This is a very com-
mon occurrence, caused by
program bugs or hardware ad-
dressing errors.

Now suppose that address
38 was the first instruction of
“yellow brick road.” Im-
mediately, the errant automa-
ton is brought under control
and the programmer is alerted
that something went wrong
before his code is destroyed by
the otherwise inevitable se-
quence of RST7 instructions
pushing the stack through all of

memory. Also, the contents of
all of the registers at the mo-
ment of the error are recorded,
which can help to find the
return path back home from Oz.

Back in Kansas

Since I have no interrupting
equipment that uses the RST7
instruction, I have found it
useful to leave this yellow-brick-
road routine at address 38 all
the time. It has saved me hours
of work more than once. By
copying Listings 1 and 2 into
your computer and properly in-
terfacing them with your TTY
routine, you’ll benefit too. Now
if someone would just find a
way of implementing Glenda
the Good. . . . ■

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** T69

Microcomputing, October 1979 171

Hardware Testing
in Suspended Animation

Few of us can afford a kilobuck logic analyzer for troubleshooting. For a small fraction of the
cost, you can construct this useful alternative.

K.D. Tentarel/i
Woodside Drive
Atkinson NH 0381 1

B ecause microcomputer
users get involved with
both hardware and software
they must also be prepared to
handle two distinctly dif-
ferent kinds of problems. All
microcomputer monitor
programs provide some
capability for software de-
bugging, but hardware de-
bugging frequently means
looking through a magnifying
glass for solder splashes. Of
course, there are logic ana-
lyzers made especially for
testing microprocessors. Un-
fortunately, many of them
cost more than a complete
hobby computer system. The
circuit described here won't
compete with commercial
logic analyzers, but it's a few
steps above a magnifying glass
in helping to solve hardware
problems. It can be built
quickly and inexpensively,
and it can continuously
observe the health of a micro-
computer while programs are
being run.

To aid in debugging soft-
ware, some system monitors
have routines which can seize
control from an operating
program when the program
reaches specified addresses
known as breakpoints. Once
the monitor is in control we
can examine the contents of
the CPU registers and tell (we

hope) what the operating
program was doing just be-
fore it was interrupted.
Running a program until a
specified test condition is met
and then putting the CPU in
suspended animation is also
an effective technique for
hardware testing.

There are at least two
situations when it can be use-
ful to temporarily suspend
CPU operation so we can
diagnose hardware problems.
The first situation arises when
we observe a system mal-
function and deduce that
information might have
gotten onto a bus when it
didn't belong there. The
second situation is when we
observe a system malfunction
which suggests that in-
formation was not put on the
bus when it should have been.
In both cases it would be
helpful to have an in-
dependent circuit keeping
tabs on the system bus while
programs were being run.

The circuit described here
is an independent judge of
system integrity which can
continuously observe any
eight leads of the system bus
and compare the word
present on those leads to a
test word which we have
specified. If the two words
are ever the same the circuit

informs us by lighting an
LED indicator and imme-
diately stops the CPU so we
can investigate further. Once
we have completed our
diagnosis we can reset the
circuit, and the program will
continue on its way as if
nothing happened.

Circuit Description

The circuit shown in Fig. 1
is designed using two 74LS85
digital comparators. Inputs to
each comparator consist of
two 4-bit words, or one byte.
When the two 4-bit words are
identical, the output (pin
6) will become a logic one
provided that the control
input (pin 3) is also a logic
one. The control input per-
mits us to operate the two
comparators as a single 8-bit
comparator by connecting
the output of I Cl to the
control input of IC2. (The
control input of IC1 will be
discussed below) Eight lines
of the microcomputer bus,
the ones we suspect are the
troublemakers, form one of
the 8-bit words, and the other
input word is the test con-
dition specified by the setting
of switch SI.

Following the comparator
is an inverter, IC3A, and an
R/S latch, IC3B and IC3D. In
normal operation, we first

172 Microcomputing, October 1979

DIPSWITCH

I C 3 — OPEN COLLECTOR 7403

WAIT

REQUEST

Fig. 1. Bus monitoring circuit. All resistors 10k unless otherwise indicated. D1 can be almost any LED.

reset the latch using push-
button switch S2 so that the
Q output is a logic zero, the
Q output is a logic one, and
the LED is extinguished. We
then begin running a pro-
gram. If the program results
in the microcomputer bus
assuming the same value as
the test condition, the R/S
latch will set, Q will become a
logic one, Q will become a
logic zero, and the LED will
light. The latch will remain
set until manually reset with
S2.

Hold It Right There

An 8080 CPU can work
with slow memory and I/O
devices because it can be
made to pause in wait states.
When the CPU is in a wait
state, address and data remain
fixed on the system buses, so
a wait state is an ideal time to
do hardware troubleshooting.
An 8080 can be put in a wait
state by placing a logic zero
on the Ready input (pin 12),
but there are some timing
restrictions which must be
observed when using the
Ready input. Most micro-
computers already contain
circuitry to satisfy the timing
requirements. Usually this is
done by synchronizing the
Ready input with the system
clock as shown in Fig. 2. The
Wait Request (or similarly

named) lead can then be
controlled asynchronously,
and it is this lead which is
normally routed to all
memory and I/O plug-in
boards.

By connecting the Q out-
put of our circuit to the Wait
Request lead we can put the
CPU into a wait state when-
ever the circuit decides that
the bus leads it is watching
are equivalent to the specified
test word. The Q output is
taken from inverter IC3C
because Wait Request inputs
must be open-collector gates.
The CPU will stay in a wait
state until our circuit is reset,
so we can take as much time
as we need to make hardware
tests. Again, once the circuit
reset button is pushed the
CPU will continue from
where it left off with no
knowledge that it had been
put in suspended animation.

One final aspect of the
circuit design which deserves
mention is the choice of
Schottky (LS) devices for the
digital comparators. Similar
comparators are made in both
standard TTL (7485) and
low-power (74L85) versions.
Most integrated circuit
suppliers who advertise in
Microcomputing carry only
standard and Schottky TTL
families. I chose Schottky
devices because their input

current is lower than standard
TTL, so they cause less
loading of the computer bus.
If your computer bus has
sufficient drive capability you
can directly substitute the
less expensive standard 7485
devices, or you can use the
74L85 devices for even less
loading if you can find them.

The Control Input as a
Qualifier

We can let the circuit look
for glitches only at certain
times by using the control
input as a timing qualifier.
For example, if we want to
study information being read
from memory we can connect
the control input to the
Memory Read (MEMR) lead
of the system control bus.
Our circuit will then respond
only when the MEMR lead is
a logic one. The control input
may also be derived from
peripheral plug-in circuits,
such as a cassette interface, so
it provides great flexibility in
troubleshooting a wide
variety of hardware problems.

If One Is Good, Two Is Better

Two such circuits can be
used independently, for
example, to observe both
input and output data buses
simultaneously. Or the two
circuits can be tied together
by connecting the control

input of one circuit to the
output of the second circuit.
This arrangement is useful for
observing a 16-bit address
bus. Two of the clip leads are
control inputs for the two
circuits, one of the leads is
the output Wait Request lead,
and the other two leads bring
5 volts and ground to the
circuit.

Check Your Addition

One of the best uses for
the circuit is as an aid in
checking out new hardware
additions to the computer
system. Imagine that you
have just plugged a new video
interface into your computer
mainframe and it doesn't
work. What do you do now?
The video interface can't be
tested easily by itself because
it depends upon signals from
the microcomputer. One way
to find out what is, or isn't,
happening is to run a program
which outputs commands to
the video interface and uses
our circuit to stop the CPU as
soon as the command is sent.
We can then use a voltmeter
or logic probe to trace the
command through the video
interface. ■

Fig. 2. There are two ways in
which Wait Requests can be
synchronized to the timing of an
8080 CPU: (a) shows the most
common method using a flip-flop;
(b) shows a method using the
newer Intel 8224 dock generator
with built-in synchronizing cir-
cuitry.

Microcomputing, October 1979 173

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i/ 0 Reader Service— see page 227

Microcomputing, October 1979 175

Steven K. Roberts
129 N. Galt Ave.
Louisville KY 40206

Sweetening the Bystesaver

While the Bystesaver is an excellent value in its original form, its usefulness can be further
enhanced by utilization of this modification.

T he Cromemco Bytesaver is
a useful addition to the cir-
cuit board repertoire of the
owner of an S-100 bus system.

Useful as both an 8K PROM
card (eight 2708s) and as a pro-
grammer for same, it is a bar-
gain at a kit price of $145. Its

utility can be even further in-
creased, however, by imple-
mentation of the technique
shown here.

Remote Programming Panel

Perhaps the single most
troublesome aspect of pro-
gramming EROMs with the
Bytesaver in its standard form
is that it is necessary to power
down the system, unplug the
board and cycle the 1C sockets
during each iteration of the pro-
gram/debug sequence. This
can wear down both the con-
nectors involved and the nerves
of the user; in my case it led to
the addition of a front-panel
programming station con-
nected to the Bytesaver by a
ribbon cable.

The result is shown in Photo
1. The sockets chosen were the
Tex-tool units (224-3344 with
receptacles) ... costly parts
but the best around for the
heavy-duty requirements of
EROM programming. Standard
24-pin sockets would work— for
a while. The switch between the
sockets replaces the program
power switch on the Bytesaver
card.

Operation

Operation of the unit is sim-
ple: A 2708 is inserted in the
socket on the right (addressed
at FC00); the switch is turned
on; and the DEBUG, ZM1 or
BYTEMOVER software is
directed to program the chip.

Photo 1. Front panel view of the Remote Programming Panel for the Cromemco Bytesaver, married to
the author’s Z-2D. The socket on the left, addressed at F800, is read-only; the one on the right, at FC00,
is for programming. The metal switch handle is a useful ground point for the elimination of bodily
static charge prior to insertion or removal of a 2708. (Photos by Douglas Fowley)

176 Microcomputing, October 1979

BYTE SAVER

CABLE

PROGRAMMING PANEL

Photo 2. Complete Bytesaver/Panel assembly. Any number of
sockets may be thus extended, but the usefulness of more than
two is questionable. DIP headers on the circuit-board end of the
cable allow separation for easy handling and installation. Elec-
trical tape around the ribbon near the board prevents insulation
puncture by 1C pins on an adjacent PC board.

After programming, the switch
is turned off. 1 The other socket
position is provided on the
panel to simplify copying data
from one EROM to another; but
this can be a two-stage affair
via system RAM if you wish to
keep socket costs to a mini-
mum (the bill from the Tex-tool
distributor was $34).

Modification

Photo 2 shows the details of
the modification. Since the on-
ly difference between the wir-
ing of the eight EROM sockets
on the card lies in the source of
the chip select signal, two
front-panel sockets may be
supported with a 24-line cable,
plus one wire for the second
select (pin 20).

A second additional wire is
added to carry the status of the
program power switch. To
allow separation of the panel
from the board and to simplify
installation, the cable should
be terminated in a 24-pin DIP
header. The two troublesome
piggyback lines, in order to be

pluggable as well, terminate in
a kludge comprising a bisected
14-pin header and a DIP socket
glued sideways onto the EROM
socket adjacent to the first one.
The other six sockets on the
Bytesaver are unaffected and
may be used as originally in-
tended.

The schematic in Fig. 1
shows how straightforward the
modification is: Wiring of the
circuit involves merely the ex-
tension of existing signals. The
only precaution to be observed,
aside from the avoidance of er-
ror, is keeping cable length at a
minimum. Crosstalk in ribbon
cable has a justifiably bad
reputation, and there is bound
to be some degradation of
pulse integrity.

A recommended step in the
prevention of trouble from this
source is the use of low-
crosstalk ribbon (available
from Spectra-Strip or surplus
from Optoelectronics in
Florida), or better still, ribbon
cable with every other line
grounded. As shown in Photo 2,

u u

Fig. 1. Schematic shows simplicity of modification: note that the on-
ly differences betwee n the two ER OM sockets are pin 18
(PROGRAM) and pin 20 (CHIP SELECT). The former is grounded on
the read-only socket, and the latter is connected to pin 20 on its cor-
responding socket on the board. The program power switch
replaces the original

I used the former and have had
no problems.

Plugging Chips

Questions arose during the
process of making the conver-
sion concerning the desirability
of plugging in the 2708s while
the socket was “hot.” My intui-
tive response was that such be-
havior was an optimal way to
destroy chips, so I checked
with Intel. The 2708 data sheet
states that power on/off se-
quences should follow a rig-
orous procedure, with Vbb (-5V)
applied prior to Vqc ( + 5V) and
Vdd ( + 12V), and with Vbb a,so
the last supply shut off.

Systems Division, which
routinely builds Intellec
Microcomputer Development
Systems with front-panel
EROM programmers, ignores
all that and allows unrestricted
plugging and unplugging of the
chips. Other programmer
manufacturers seem to do the
same (in fact, I could find no in-
dustrial user who followed the
Intel specifications), so I con-
cluded that the little devices

are tougher than their makers
suggest.

Whatever the case, the unit
shown in the photographs has
programmed about thirty 2708s
since it arose from the bench
clutter, and they all perform
their function uneventfully.

Free At Last!

The modified Bytesaver
brings out of the closet much of
the latent usefulness in the
original design. Freed from the
gut-wrenching thermal cycling
associated with frequent
power-up/down sequences, the
process of system development
Involving EROMs is almost
pleasant.

It is no longer a necessary
chore to disassemble your
rack-mounted processor in
order to change a status bit in
your I/O driver or to copy a pro-
gram for an associate, and con-
tact wear, both on the ven-
erable S-100 bus and on the ill-
suited Tl sockets, is kept to a
safe minimum. It might even be
possible to screw on the cover
and forget it for a while! ■

Wote: Locations in the 2708 can be changed from a 1 to a 0 by even a “normal” write cycle when program power is on. Always be
sure to leave the switch OFF when not actually burning a ROM. The error can be extremely frustrating, especially with the
Cromemco ZM1 monitor, which starts at FFFF and seeks downward for the first RAM into which to place its stack. The “RAM”
might turn out to be the program you just placed in ROM!

Microcomputing, October 1979 1 77

*xN15

By Netronics

ASCII/BAUDOT
STAND ALONE

Computer Sjj*
Terminal

The Netronics ASCII/BAUDOT Computer Terminal Kit is a
microprocessor-controlled, stand alone keyboard/terminal
requring no computer memory or software. It allows the use of
either a 64. or 32 character by 16 line professional display for-
mat with selectable baud rate, RS232-C or 20 ma. output, full
cursor control and 75 ohm composite video output.

The keyboard follows the standard typewriter configuration
and generates the entire 128 character ASCII upper/lower case
set with 96 printable characters. Features include onboard
regulators, selectable parity, shift lock key, alpha lock jumper,
a drive capability of one TTY load, and the ability to mate
directly with almost any computer, including the new Ex-
plorer/85 and ELF products by Netronics.

The Computer Terminal requires no I/O mapping and
includes lk of memory, character generator, 2 key rollover,
processor controlled cursor control, parallel ASCII/BAUDOT
to serial conversion and serial to video processing— fully
crystal controlled for superb accuracy. PC boards are the
highest quality glass epoxy for the ultimate in reliability and
long life.

VIDEO DISPLAY SPECIFICATIONS

The heart of the Netronics Computer Terminal is the micro-
processor-controlled Netronics Video Display Board (VID)
which allows the terminal to utilize either a parallel ASCII or
BAUDOT signal source. The VID converts the parallel data to
serial data which is then formatted to either RS232-C or 20 ma.
current loop output, which can be connected to the serial I/O
on your computer or other interface, i.e., Modem.

When connected to a computer, the computer must echo the
character received. This data is received by the VID which
processes the information, converting to data to video suitable
to be displayed on a TV set tusing an RF modulator) or on a
video monitor. The VID generates the cursor, horizontal and
vertical sync pulses and performs the housekeeping relative to
which character and where it is to be displayed on the screen.
Video Output: 1.5 P/P into 75 ohm (E1A RS-170) • Baud Rate:
1 10 and 300 ASCII • Outputs: RS232-C or 20 ma. current loop
• ASCII Character Set: 128 printable characters—

aBT5«9vXpvlWaflo 41 , 0 *t^X|«^
! 'ttt*' <)*♦,- . /0123456789 : ;<*>?
0flBCOEFGHIJKLMNOPORSTWVXYZCvl A _
v abcdef ?Ki jklnftopqrstuwx¥Z< INI

BAUDOT Character Set: A BCDEFGHIJKLMNOPQ
RSTUVWXYZ-?:*3$$()., 9014! 57; 2/68*
Cursor Modes: Home, Backspace, Horizontal Tab, Line Feed,
Vertical Tab, Carriage Return. Two special cursor sequences
are provided for absolute and relative X-Y cursor addressing •
Cursor Control: Erase, End of Line, Erase of Screen, Form
Feed, Delete • Monitor Operation: 50 or 60Hz (jumper
selectable.

Continental U.S.A. Credit Card Buyers Outside Connecticut

CALL TOLL FREE 800-243-7428

_ To Order From Connecticut Or For Technical M

r Assistance. Etc. Call (203) 354-9375 ■

I Netronics R&D Ltd., Dept. PE-9
333 Litchfield Road, New Milford, CT 06776
| Please send the items checked below—

I D Netronics Stand Alone ASCII Keyboard/Computer ■
Terminal Kit, $149.95 plus $3.00 postage & handling. |

I D Deluxe Steel Cabinet for Netronics Keyboard/Termi- .
nal In Blue/Black Finish, $19.95 plus $2.50 postage |

I and handling.

□ Video Display Board Kit alone (less keyboard), $89.95 |

I plus $3 postage & handling.

□ 12” Video Monitor (10 MHz bandwidth) fully assem- I

I bled and tested, $139.95 plus $5 postage and handling. _
□ RF Modulator Kit (to use your TV set for a monitor), |

I $8. 95 postpaid.

□ 5 amp Power Supply Kit In Deluxe Steel Cabinet I

I (±8VDC @ 5 amps, plus 6-8 VAC), $39.95 plus $2 J
postage & handling.

I Total Enclosed (Conn. res. add sales tax) $ .

By-

I D Personal Check □ Cashiers Check/Money Order -

□ Visa □ Master Charge (Bank # ) |

I Acct. #

Signature _

Print
Name .

_Exp. Date

■ Address
City

|^State

_Zip

□ Send Me More Information mm J

ATTENTION TRS-80 OWNERS

Now available to supplement 'Sound-Pac' is Sound-Patch! The con-
cept patches your existing programs to use 'Sound-Pac' to generate
sound for your programs. A list of available patches is in our brochure.

Stock Market Analizer — Now let your TRS-80 be your stock
broker by plotting a 120-day moving average for you. We have over
200 stocks in our database to choose from, with more being added
daily. List of stocks and information in our brochure.

Telephone Dialing System — Let your TRS-80 dial and remember
all your calls with only a flip of your fingers.

L. II 4k Software & Schematic S 6.95

L. II 4k Software & Asmb. Hardware $39.95

Bowlstat - Now you have your TRS-80 keep a complete record of
all those league stats quick and easy. A league secretary can't be
without one.

Manual $ 4.95

DOS 32k Printer on diskette $34.95

-Other Simulations-

SOUND Pac Generates sound for TRS 80 L. II 4k $14.95

BAKER STREET-Great detective game L. II 16k 6-00

PARTY-Fun at a college dorm L. II 16k 8.00

AIRPORT Be an airline tycoon L. II 16k 8.00

ONE ON-ONE-Basketball game L. II 16k 8.00

PRO BOXING Crown your own champ L. II 16k 10.00

HORSE RACING Like being at the track L. II 16k 8.00

CHIVALRY Bo a knight of the round L. II 16k 8.00

BIORYTHUM-Chart your biorythum L. II 4k 5.00

YATTZZEE Old standard L. II 16k 3.00

Many more in our FREE brochure
Please add $1.00 postage and handling
Ohio residents add 4% sales tax

REAL-LIFE Simulations
3107 Ridge Rd.

Warren, Ohio 44484

R32

6800 SS50 16K SYSTEMS

Includes: Mainframe cabinet, mother board, power
supply, fan, CPU. 16K static RAM. and choice of I/O
card $1294.29

Other packages available.

16K STATIC RAM BOARDS — SS50

Gold Bus connectors — DIP switch controllable
addressing, write protect and enabeling of each 4K

block. Tested at 2 MHz Assembled $298.13

Above but socketted and with software control registers.

Assembled $368.16

TI TMS 4044’ s:

450 ns $5.00 each

250 ns $6.00 each

2708 s $7.90 each

These are factory prime chips from same shipments we use in
our professional quality boards

Add $10 handling on orders under $200.

cimix

1337 W. 37th Place • Chicago, IL 60609
(312)927-5510 • TWX 910-221-4055

The Company that delivers.

Quality Electronic products since 1975.

GIMIX’ and GHOST" are registered trademarks of GIMIX INC

FRE&fe.

* SORCERER „„

Z80 Processor
Full-size ASCII Keyboard
Calculator Style Numeric Pad
8K RAM (up to 48K RAMi
Resident 4K Monitor ROM
Interchangeable ROM Pacs

with 8K RAM

Dual Cassette I/O
Serial and Parallel I/O
30 x 64 Character Display
240 x 512 Graphics Resolution
64 User Defineable Characters
S-100 Compatable

^ e List Price
$ 995.

Receive FREE Cassette Recorder value $67

with 16K RAM 1145.

Receive FREE 12” Video Monitor Value $149
with 32K RAM 1295.

Receive FREE Monitor and Recorder Value $216

with 48K RAM 1445.

Receive FREE Monitor and Recorder

PLUS Extended BASIC Value $265

WE PAY ALL SHIPPING AND HANDLING CHARGES
Shipment stock to 30 days. Connecticut residents please add 7% sales tax.

MCK© DISCO im/ SUffyJSl

198 General Lyon Rd., Eastford, CT 06242

203-974-1214 *xM116

12” BLACK & WHITE
LOW COST VIDEO
TERMINAL

Easily interfaced with Radio Shack TRS 80

$149.00 LIST

Will sell 6 feet coaxial cable $5.00
Add $5 for shipping and handling in Continental U.S.A.

• Ideal for home, personal and business computer systems:
surveillance monitors • 12" diagonal video monitor • Com-
posite video input • Compatible with many computer
systems • Solid-state circuitry for a stable & sharp pic-
ture • Video bandwidth— 12 MHz :£3 DB • Input im-
pedance— 75 Ohms • Resolution— 650 lines Minimum IN
Central 80% of CRT; 550 Lines Minimum beyond central 80%
of CRT ref EIA RS-375 • Dimensions— 1 1 .375" high; 16.250"
wide; 11.250" deep (exclude video input con-
nector) • Weight— 6.5 KG (14.3 lbs) net

Use Master Charge/Visa or send money order.

Micro Products Unlimited

P.O.Box 1525, Arlington, TX 76010
817/461-8043
Dealer inquiries welcome

M81

OSI SOFTWARE OSI

FOR

OHIO SCIENTIFIC

25 PROGRAMS

ALL ORIGINAL ALL IN BASIC
ALL RUN IN 4K ALL ON TAPE
ALL WELL DOCUMENTED
ALL AVAILABLE FOR Cl, C2, AND
SUPERBOARD

Our 50c catalog includes a free game listing, pro-
gramming hints, POKE locations, and other stuff OSI
forgot to mention.

* * * SPECIALS * * *

CHESS FOR OSI S 19.95

(not in bosic, specify system).

NEW GRAPHICS DOMDER $4.95

AARDVARK

TECHNICAL

SERVICES

1690 BOLTON, WALLED LAKE
Ml 48088 313-624-6316

178 Microcomputing, October 1979

— Professional —

Real Estate Programs

available on cassette or diskette

for Apple & TRS-80 II

Property Management System

• Rental Income Tracking

• Complete Expense Analysis

System w/Manual $125.00
Manual $10.00

Program Modules:

1) Home Purchase Analysis

2) Income Property Cashflow/ Leverage

3) Construction Cost/ Profit

4) Tax Deferred Exchange

5) APR Loan Analysis

<1N

I loftware
^ealtj |om

Price Per Module $20.00
Add $5.00 for Programs
on Diskette

oftware At Computer Stores
everywhere or call
lompany (213) 372-9419

for C.O.D. v 0 R33

2045 Manhattan Ave., Hermosa Beach, CA 90254

TRS-80

Scientific Library Vol. 1

• ROOTS OF EQUATIONS

• DIFFERENTIATION AND INTEGRATION

• SIMULTANEOUS EQUATIONS

• MATRIX OPERATIONS (determinant, inversion, eigen-
values. etc.)

• LEAST SQUARE ANALYSIS (curve fittings, lineor
regression, polynomial regression, multiple regres-
sion)

• ORDINARY DIFFERENTIAL EQUATIONS (initial value
problems, simultaneous equations, stiff equations)

• PARTIAL DIFFERENTIAL EQUATIONS (a doss of PDE)

• STATISTICS (median, variance, standard deviation,
etc.)

• PLOTTING (display of data and functions)

For educators, scientists, engineers, researchers and
those interested in serious computing with TRS-80.
Complete documentation of above programs including
program listings, detailed descriptions, brief theory,
references and application examples.

All programs tested and ready for run with TRS-60 (level
H, 16K).

$ 1 2.00 send check or money order to» v* L3
- r 5819 Thomas Ave.,

^ JwPP Philadelphia PA 19143

FOOTBALL ON TRS-80

l€V€L I 4K

• Most realistic football game ever
designedl

• Choice of 7 offensive plays and 6
defensive plays with 476 possible
outcomes for each playl

• Field goals, normal and coffin-corner
punts, time-outs, fumbles, inter-
ceptions, QB-sacMs, safeties — all
there I

• Graphic Display

Send $9.95 / cassette to:

Computer Simulations Canoda
*144-3225 Uplands Dr.

Ottawa, Ontario, Canada K1V 9V3

^C153

Level "A" at $129.95 is a
complete operating system,
perfect for beginners, hob-
biests, or industrial con-
troller use.

Start Computing For Just $129.95 With An
8085-Based Professional Computer Kit—

Explorer/85

700% compatible with all 8080A and
8085 software & development tools!

No matter what your future computing plans may
be, Level “ A ” — at $129.95 — is your starting point.

Starting at just $129.95 for a Level “A ” operating system,
you can now build the exact computer you want. Explorer/ 85
can be your beginner's system, OEM controller, or IBM-
formatted 8" disk small business system. . .yet you're never
forced to spend a penny for a component or feature you don *t
want and you can expand in small, affordable steps!

Now, for just $129.95, you can own the first level of a fully
expandable computer with professional capabilities— a com-
puter which features the advanced Intel 8085 epu, thereby
giving you immediate access to all software and development
tools that exist for both the 8085 and its 8080A predecessor
(they are 100% software compatible )—& computer which
features onboard S-100 bus expansion— plus instant conver-
sion to mass storage disk memory with either 5-1/4” diskettes
or standard IBM-formatted 8” disks.

For just $129.95 (plus the cost of a power supply, keyboard/
terminal and RF modulator, if you don’t have them already),
Explorer/85 lets you begin computing on a significant level. . .
applying the principles discussed in leading computer maga-
zines. . .developing ‘‘state of the art” computer solutions for
both the industrial and leisure environment.

Level “A” Specifications

Explorer/85’s Level “A” system features the advanced Intel
8085 epu, an 8355 ROM with 2k deluxe monitor/operating
system, and an 8155 ROM-I/O— all on a single motherboard
with room for RAM/ROM/PROM/EPROM and S-100 ex-
pansion, plus generous prototyping space.

(Level “A” makes a perfect OEM controller for industrial
applications and is available in a special Hex Version which
can be programmed using
the Netronics Hex Keypad/
Display.)

PC Board: glass epoxy, plated
through holes with solder mask
• I/O: provisions for 25-pin
(DB25) connector for terminal
serial I/O, which can also sup-
port a paper tape reader
...provision for 24-pin DIP
socket for hex keyboard/dis-
play. . .cassette tape recorder in-
put ... cassette tape recorder output .. .cassette tape control
output. . .speaker output. . . LED output indicator on SOD
(serial output) line. . .printer interface (less drivers). . .total of
four 8-bit plus one 6-bit I/O ports •Crystal Frequency: 6.144
MHz • Control Switches: reset and user (RST 7.5)
interrupt. . .additional provisions for RST 5.5, 6.5 and TRAP
interrupts onboard • Counter/Timer: programmable, 14-bit
binary • System RAM: 256 bytes located at F800, ideal for
smaller systems and for use as an isolated stack area in
expanded systems. . . RAM expandable to 64k via S-100 bus or
4K on motherboard.

System Monitor (Terminal Version): 2k bytes of deluxe
system monitor ROM located at F000 leaving 0000 free for user
RAM/ROM. Features include tape load with labeling . . .tape
dump with labeling. . .examine/change contents of memory
...insert data... warm start. . .examine and change all
registers. . .single step with register display at each break point,
a debugging/training feature. . .go to execution address...
move blocks of memory from one location to another. . .fill
blocks of memory with a constant . . . display blocks of memory
. . .automatic baud rate selection. . .variable display line length
control (1-255 characters/line). . .channelized I/O monitor
routine with 8-bit parallel output for high speed printer...
serial console in and console out channel so that monitor can
communicate with I/O ports.

System Monitor (Hex Version): Tape load with labeling. . .
tape dump with labeling. . .examine/change contents of mem-
ory... insert data... warm start. . .examine and change all

f" Ne!ron!c?R LuT,

I 333 Litchfield Road. New Milford, CT 06676

Please send the items checked below — p i us $2 p&ii .

□ Explorer/85 Level “A” Kit (ASCII “

Version), $129.95 plus $3 p&h.

□ Explorer/85 Level “A” Kit (Hex
Version), $129.95 plus $3 p&h.

□ 8k Microsoft BASIC on cassette
tape, $64.95 postpaid.

□ 8k Microsoft BASIC in ROM Kit
(requires Levels ”B,” “D,” and ”E”),

$99.95 plus $2 p&h.

□ Level “B” (S-100) Kit, $49.95 plus
$2 p&h.

□ Level *‘C” (S-100 6-card expander)

Kit, $39.95 plus $2 p&h.

□ Level *‘D” (4k RAM) Kit, $69.95

plus $2 p&h.

□ Level *‘E” (EPROM/ROM) Kit,

$5.95 plus 50« p&h.

□ Deluxe Steel Cabinet for Explorer/

85, $49.95 plus $3 p&h.

□ ASCII Keyboard/Computer Ter-
minal Kit (features a full 128 character
set, upper & lower case, full cursor con-
trol, 75 ohm video output convertible
to baudot output, selectable baud rate,

RS232-C or 20 ma. I/O, 32 or 64 char-
acter by 16 line formats, and can be

By Netronics

mmm

I used with either a CRT monitor or a TV
set (if you have an RF modulator),
$149.95 plus $2.50 p&h.

□ Deluxe Steel Cabinet for ASCII
Keyboard/Terminal, $19.95 plus $2.50
p&h.

□ Power Supply Kit ( ± 8V @ 5 amps)
in deluxe steel cabinet, $39.95 plus $2
p&h.

□ Gold Plated S-100 Bus Connectors,
$4.85 each, postpaid.

□ RF Modulator Kit (allows you to
use your TV set as a monitor), $8.95
postpaid.

□ 16k RAM Kit (S-100 Board expands
to 64k), $199.95 plus $2 p&h.

□ 32k RAM Kit, $329.95 plus $2 p&h.

□ 48K RAM Kit, $459.95 plus $2 p&h.

□ 64k RAM Kitp$589.95 plus $2 p&h.

□ 16k RAM Expansion Kit (to expand
any of the above up to 64k), $139.95
plus $2 p&h each.

□ Intel 8085 epu User’s Manual, $7.50

postpaid.

□ Special Computer Grade Cassette
Tapes, $1 .90 each or 3 for $5, postpaid.

□ 12” Video Monitor (10 MHz band-
width), $139.95 plus $5 p&h.

□ North Star Double Density Floppy
Disk Kit (One Drive) for Explorer/
85 (includes 3 drive S-100 controller,

registers . . . single step with register display at each break point
. . .go to execution address. Level ‘‘A” in the Hex Version
makes a perfect controller for industrial applications and can
be programmed using the Netronics Hex Keypad/Display.

ICTI MBS?”” Hex Keypad/Display
Specifications

Calculator type keypad with 24
v* T £\ ; V w ' system defined and 16 user

• ^ defined keys. 6 digit calculator

type display which displays full
address plus data as well as
Hex Keypad/Display. register and status information.

Level “B” Specifications

Level“B” provides the S-100 signals plus buffers/drivers to
support up to six S-100 bus boards and includes: address
decoding for onboard 4k RAM expansion select-able in
4k blocks. . .address decoding for onboard 8k EPROM expan-
sion selectable in 8k blocks. . .address and data bus drivers for
onboard expansion. . .wait state generator (jumper selectable),
to allow the use of slower memories. . .two separate 5 volt
regulators.

Level “C” Specifications

Level “C” expands Explorer’s
motherboard with a card cage,
allowing you to plug up to six
S-100 cards directly into the
motherboard. Both cage and
Explorer/85 with level cards are neatly contained inside
"C" card cage. Explorer’s deluxe steel cabinet.

Level “C” includes a sheet metal superstructure, a 5-card gold
plated S-100 extension PC board which plugs into the mother-
board. Just add required number of S-100 connectors

Level “D” Specifications

Level “D” provides 4k or RAM, power supply regulation,
filtering decoupling components and sockets to expand your
Explorer/85 memory to 4k (plus the original 256 bytes located
in the 8 155 A). The static RAM can be located anywhere from
0000 to EFFF in 4k blocks.

Level “E” Specifications

Level “E” adds sockets for 8k of EPROM to use the popular
Intel 2716 or the T1 2516. It includes all sockets, power supply
regulator, heat sink, filtering and decoupling components.
Sockets may also be used for soon to be available RAM IC’s
(allowing for up to 12k of onboard RAM).

Order A Coordinated
Explorer/85 Applications Pak!

Experimenter’s Pak (SAVE $12.50)— Buy Level “A” and Hex
Keypad/Display for $199.90 and get FREE Intel 8085 user’s
manual plus FREE postage & handling!

Student Pak (SAVE $24.45)— Buy Level “A,” ASCII Key-
board/Computer Terminal, and Power Supply for $319.85 and
get FREE RF Modulator plus FREE Intel 8085 user’s manual
plus FREE postage & handling!

Engineering Pak (SAVE $41.00)-Buy Levels ‘‘A,” “B,”
“C,” *‘D,” and *‘E” with Power Supply, ASCII Keyboard/
Computer Terminal, and six S-100 Bus Connectors for $514.75
and get 10 FREE computer grade cassette tapes plus FREE
8085 user’s manual plus FREE postage & handling!

Business Pak (SAVE $89.95)— Buy Explorer/85 Levels “A,”
“B,” and “C” (with cabinet), Power Supply, ASCII Key-
board/Computer Terminal (with cabinet), 16k RAM, 12”
Video Monitor, North Star 5-1/4” Disk Drive (includes North
Star BASIC) with power supply and cabinet, all for just
$1599.40 and get 10 FREE 5-1/4” minidiskettes ($49.95 value)
plus FREE 8085 user’s manual plus FREE postage & handling!

Continental U.S.A. Credit Card Buyers Outside Connecticut

CALL TOLL FREE 800-243-7428

To Order From Connecticut Or For Technical

Assistance, Etc. Call (203) 354-9375 “ "|

sonalized disk operating system— just ■
plug it in and you’re up and running!),!
$699.95 plus $5 p&h.

□ Power Supply Kit for North Star!
Disk Drive, $39.95 plus $2 p&h.

□ Deluxe Case for North Star Disk!
Drive, $39.95 plus $2 p&h.

□ Experimenter’s Pak (see above),!
$199.90 postpaid.

□ Student Pak (see above), $319,851
postpaid.

□ Engineering Pak (see above), I
$514.75 postpaid.

□ Business Pak (see above), $1599.40 1
postpaid.

T otal Enclosed $ I

^N15

S 'onn. res. add sales tax) By— ■

Personal Check □ M.O. /Cashier’s |
Check □ Visa □ Master Charge ■

(Bank tt )l

Acct. 8 _
Signature _
Print

Name

_Exp. Date _

Address
City

[J1U3 pan. \mviuuvo J U 1 I»W WUUllUUCI)

□ Hex Keypad/Display Kit, $69.95 DOS, and extended BASIC with per- State

_Zip_

Send Me Information i

f ^ Reader Service — see page 227

Microcomputing, October 1979 1 79

ALL NEU

a ass ras;

TEXAS INSTRUMENT COMP

T I 99-4 COMPUTER

$ 995.

T I 810 BASIC PRINTER

$1590.

T I 820 BASIC PRINTER

$1990.

T I SOFTWARE

$SAVE

CENTRONICS PRINTERS

779-2 TRAC. FD

$949.

779-1 FRIC.FD

$890.

730-1 NEU PRNTR

$799.

730-3

$849.

MICRO PI $390. MICRO SI

$475.

COMMODORE BUSINESS MACHINES

PET 2001-8K

$675.

PET 2001 - 1 AN , B

$859.

PET 200 1 -32N , B

$1090.

PET 2040 DUAL FLOPPY

$1090

PET 2022 TRAC.FD PRINTER

$849.

PET 2023 FRIC.FD PRINTER

$749.

NORTH STAR COMPUTERS

BIG $$ SAVINGS
INTERTEC SUPERBRAIN

THE HONOR GRADUATE COMPUTER
DISPLAY TERMINALS

$2990

INTERTUBE II

$775

HAZELTINE 1400

$690.

1410

$785

1500

$950.

1510

$1 149

COMPRINT PINTERS

COMPRINT 912 PAR

$449.

COMPRINT 912 SER

$499.

MULTI-BUSINESS COMPUTER SYSTEMS
28 MARLBOROUGH STREET
PORTLAND , CONN. 06480
(203) 342-2747

is M83

“Old” PET Owners:

The Basic Switch™ allows you switch selectable use of
“Old" and “Retrofit" ROM sets. Insert both sets in a small
case that sits beside your PET. Slip the wiring harness into
your original ROM sockets. Flip The Basic Switch to select
a ROM set your PET does an automatic reset and you're
up and running. Model 15 adds a zero insertion force 15th
socket for ROMs like the BASIC Programmer's Toolkit. And
you save the cost of the $25.00 board. The Model 15 al-
lows switch selection of 2716 (2K) or 2732 (4K) type ROMs
for the 15th socket. Order The Basic Switch with ROM Re-
trofit installed and save $5.00.

Ordering Information: “Old" PETs shipped with 24 or 28
pin ROMs. Specify which you need at time of order. Toolkits
available for “Old" ROMs and "Retrofitted" ROMs. Master-
charge and Visa accepted. N.C. residents add 4% sales
tax. Add $2.50 shipping /handling per unit.

The Basic Switch Series + Retrofit

Model 14-E $64.95

Model 14-D $77.95

Model 15-A $99.95

Model 15-A with installed Retrofit ROMs and one version Toolkit: $229.95
Model 15-A with installed Retrofit ROMs and both Toolkits: $274.95

Only Model 15 has additional socket. Note savings on "package" systems.

$149.95

$162.95

$184.95

Small System Services, Inc.

900-902 Spring Garden Street
Greensboro, N.C. 27403
919-272-4867

^sm

PET is a trademark of Commodore Business Machines, Inc. The Basic Switch is a trademark of
Small System Services, Inc. The BASIC Programmer's Toolkit is a trademark of Palo Alto ICs,

A Division of Nestar Systems, Inc.

. v v v v v v v v v v v v v v v v v v v v v •;« *> * *> * * * * * * .> .> ♦> *

dilH : TT?e 7 n dependent Deu>s letter Mealh Co.Compulers

%ul or Teatu res

Hardware modifications
developed b y readers

information on compatible
f^arduta^e and Software
from other vendors

Advance information art

forthcoming HeaVp Co.
computer -products

Reports of users ’ experiences
u>iH? tt?ei r systems

i/” B43

S pecial Reports
Tpe "Printer

1T>e SC-1108'

Learning Program f
Assembly (anquay e

mailed first class (airmail
overseas X Send $ 81? 5 for H issues
or $15,15 for 24* (overseas |f4f/f 2;
$25/24 pay able on a US bank) you
Ipave tjpt epo ice of starting w\\)p
the latest issue or available back
issues (about S')*

8li££, 3 25 ~K Penn s u Ivanta Ava, S. C ; ID a s hi ng fo n , D. C* 2 0003

180 Microcomputing, October 1979

TRS-80 ... all business! !

...with CP/M, CBASIC2,

& applications software.

CP/M Operating System (w/Editor, Assembler,

Debugger, Utilities & 6 manual set) $150

CBASIC2 Compiler (w/manual) $ 95

DESPOOL Print Spooler (w/manual) $ 75

♦Osborne & Assoc. PAYROLL W/COST

ACCTNG $250

♦Osborne & Assoc. ACCTS. RECEIVABLE &

ACCTS. PAYABLE $250

♦Osborne & Assoc. GENERAL LEDGER $250

*=CBASIC2 source programs; add $15 (each) for
applicable O & A book.

APH - Self-administered Automated Patient

History $175

DOWNLOAD - TR-80 (or other)

CP/M to CP/M $95

data/program (source or object) transfer over
RS232 link

Send 3CW SASE for add'l. Software avail, (including
CP/M Users Group software) and FREE "CP/M Primer."
CA residents add 6% tax. Visa, M/C, M/O, Check OK.

M 1C ivlg. ie LR IN HE. IT. (714) 848-1922
N ^C129

IS-

8041 NEWMAN AVENUE • SUITE 208 • HUNTINGTON BEACH. CALI FORNI A 92647

• Take your favorite character— or
let the computer create one for
you!

• Let the Book of Lore guide you
through a DUNJONQUEST"
within the Temple.

• Decide to fight the monsters or
grab the treasure and run— but
don’t think too long— they’ll come
after you!

The Temple of Apshai— for the
TRS-80 (Level II, 16K) and PET
(32K) microcomputers.

Ask your local dealer
or send a check for $24.95 to:

Automated Simulations— Department B, P.0. Box 4232,
s A7i Mountain View, CA 94040

California residents please add 6% sales tax.

The Vault of the Dead is
but one of the many
dark and fearsome
mysteries within the
ruined Temple of
Apshai. The Temple of
Apshai is your first
adventure in the
DUNJONQUEST™ series
of fantasy role playing
games.

DUNJONQUEST™ is a
complete game system
and The Temple of Apshai
is a complete fantasy
adventure game for you
and your microcomputer.

OVER. 200 KOOH* ! .
OVER 30 HONiTEtel
OVER 70 TREASVZes/

m INFINITE BASIC eo

RELOCATABLE MODULES FOR THE TRS LEVEL II AND DOS SYSTEMS

LOAD ANY OR ALL MODULES. FOR $49.95 THE CORE PACKAGE INCLUDES:

80 MATRIX PACKAGE oc 80 STRING PACKAGE 80

Over 30 BASIC commands including:

oo Matrix Read, Inverse, Transpose, and Identity.

Simultaneous Equations! ! !

oo Add, Subtract, or Multiply Scalars, Vectors, or Multi-
dimension arrays!!!

oo Dynamically Reshape, Expand, Delete Arrays, Change
arrays in mid-program.

oo Copy array elements, set arrays to scalar, zero arrays,
move arrays.

Tape array read and write including string arrays.

FOR $29.95 more get the °© BUSINESS PACKAGE oo

oo Eliminate round-off error!! Multiple precision packed
decimal arithmetic. 127-digit max. accuracy
oo Binary search or sorted arrays. Insert new elements in
sorted arrays!!!

oo Automatic page headings, footings, and pagination.
Includes forced end-of-page.

oo Automatic hash for record retrieval!! And more for your
professional packages.

COMMAND PROCESSOR ‘COMPROC’ for $19.95 (DOS only)

Over 40 BASIC commands including:

oo Left and right justify, truncate, rotate. Text justification.
String centering.

oo Delete or insert substring, Pack strings, Convert to upper
or lowercase.

oo Translate characters, Reverse strings, Verify function,
Number of occurrences.

oo Masked string searches for simple or array variables.
Encrypt or decrypt strings.

oo Compress/uncompress character string arrays to 6 bits or
less per character.

oo AND the famous RACET machine language SORTS. Multi-
key multivariable and string. Sort 1000 elements in 9 sec!!

FUTURE oo ADD-ON PACKAGES o© will include
oo STATISTICS oo INPUT/OUTPUT oeGRAPHICS oo

Attn: TRS Add-On OEM’s: We can support your special
hardware add-ons with direct BASIC commands.

System Houses: We license System House usage of
oo INFINITE BASIC oo modules.

Check, VISA, M/CC.O.D.
Calif, residents add 6%

Telephone Orders Accepted
(714)637-5016

WHEN ORDERING PLEASE
ADVISE PUBLICATION SOURCE

RACET COMPUTES
702 Palmdale, Orange CA 92665

Extend DOS-AUTO command to perform multiple steps either at power-up or as a user command.
Execute a script consisting of a sequence of commands or data from a BASIC command file.

REMODEL + PROLOAD for $34.95 (Specify 16, 32, or 48K version)

REnumber any section of a program, MOve program segments, DEIete program lines.

Combine programs with renumber and merge. Load or save any portion of program from tape.

DISK SORT PROGRAM ‘DOSORT’ for $34.95 (Specify 32 or 48K, minimum 2 disk system)

SORT/MERGE multi-diskette sequential files. Multiple variables and keys.

Includes machine language in-memory sorts, comparators and string handling. R24

COPY SYSTEM TAPES with ‘COPSYS’ for $14.95 (Non-DOS)

TRS-80 PRODUCTS

Iol tM is S51

r^MALL

k-lYSTEM

ADVENTURE 1 - ADVENTURELAND - $14.95 each or
ADVENTURE 2 - PIRATE'S ADVENTURE - all three for
ADVENTURE 3 - MISSION IMPOSSIBLE - only $39.95.

Machine language versions of Adventure, the current rage of the big
time-sharing computers! 100+ word vocabulary! 30 rooms and locations. A
challenge that can take weeks to solve! LEVEl-II 16K.

TRS232 PRINTER INTERFACE - $49.95 (+$2.00 shipping)

Assembled and tested output port for TRS-80 printing. Use any RS-232 or
20-mil current loop ASCII printer. Expansion interface not required. Use
with LEVEL-II BASIC, CP/M, BASIC-IP, ELECTRIC PENCIL, RSM-2/2D or your own
programs! Standard cassette software included, or order new "FORMATTER" for
$9.95 with TRS232 (see below).

RSH-1S: A MACHINE LANGUAGE MONITOR FOR 4K TRS-80 *S - $23.95
RSN-2: AN ADVANCED MONITOR FOR 16K TRS-80'S - 26.95
RSM-2D: THREE MONITORS FOR TRS-80 DISK SYSTEMS - 29.95

22 commands to control your TRS-80 Z-80 processor! Examine ROM's, test RAM,
program in machine language, read/write machine language tapes, and much
more! A SYMBOLIC DUMP command disassembles memory into Z-80 mnemonics!
Display memory in HEX or two ASCII formats, or EDIT, MOVE, EXCHANGE, VERIFY,
FILL, ZERO, TEST, or SEARCH your memory! RSM-2/2D include all above
features, plus read/write SYSTEM tapes, enter BREAKPOINTS, PRINT with our
TRS232 or the expansion interface, and read/write disk sectors directly!
RSM-2 loads at the top of 16K LEVEL I or II. RSM-2D, furnished on disk, has
3 versions for 16K, 32K and 48K.

BASIC-IP - LEVEL-1 BASIC WITH PRINTING! - $19.95

TRS232 "FORMATTER" SOFTWARE PACKAGE - $14.95

Page and line length control, form feed function, printer pause, 9 baud
rates, "smart" line termination, built-in keyboard debounce, software
control of screen printing, etc. $9.95 if ordered with TRS232.

THE ELECTRIC PENCIL FOR TRS-80 DISK SYSTEMS - $150.00
THE ELECTRIC PENCIL FOR TRS-80 TAPE SYSTEMS - 99.95

Write text, delete, insert, or move words, lines or paragraphs, save text on
tape (or disk), then print formatted copy with our TRS232 or Centronics
printer (RS-232-C with disk version). Right justification, page titling and
numbering, transparent cursor and repeating keyboard. Lowercase entry and
display with minor modification. LEVEL-I or II 16K (Tape version).

CP/M OPERATING SYSTEM WITH TRS232 SOFTWARE - $145.00

Run any LEVEL-1 BASIC tape (12K or less) in 16K LEVEL-II TRS-80 without
conversion! Plus LLIST and LPRINT for TRS232, RS-232-C or Centronics
printers. LPRINT ON and LPRINT OFF prints anything that you see on the
screen! All LEVEL-I abbreviations and functions supported.

BARRICADE: MACHINE LANGUAGE ACTION GAME FOR TRS-80'S - $14.95

Break through 5-wall Barricade with high-speed ball and keyboard controlled
paddle! Trap the ball among the walls and watch it destroy the 100 blocks!
Select 96 different options to challenge experts and beginners. 3 scores
with the best of each saved to be challenged by other players. NOBODY can
achieve the maximum WEIGHTED SCORE of 33,000! 4K LEVEL-I and II.

AIR RAID: MACHINE LANGUAGE TRS-80 SHOOTING GALLERY! - $14.95

Shoot down high speed aircraft with a ground based missile launcher!
Aircraft explode dramatically when hit, sometimes destroying other nearby
planes! Score is tallied for each hit or miss, and the highest score is
saved to be challenged by other players. Hours of fun for you, and a super
demonstration program for entertaining friends! 4K LEVEL I and II.

* CALIFORNIA RESIDENTS ADD 6 PER CENT SALES TAX *

* SMALL SYSTEM SOFTWARE * P.O. BOX 366 * NEWBURY PARK, CALIF.

91320 * W

SMALL SYSTEM SOFTWARE/LIFEBOAT ASSOCIATES version of CP/M. Includes TRS232
and RS-232-C software, lower-case support, debounce, plus DCV-2 and other
unique utilities. CP/M Editor creates and modifies all files. Files may be
much longer than your memory! Assemble directly from disk, placing HEX and
PRINT files back onto disk! Includes DDT (Dynamic Debugging Tool), PIP
(Peripheral Interchange Program), and more! 16K single disk required, 32K
dual disk recommended.

DCV-1 : CONVERT SYSTEM PR06RAMS TO DISK FILES - $9.95

Execute Adventure, Barricade, Air Raid, RSL-1, ESP-1, T-BUG, etc., from
disk, even if they interfere with TRSDOS! After using DCV-1, your program
loads from disk into high memory, moves itself to its correct address, then
jumps there and executes!

OTHER TRS-80 PRODUCTS

ESP-1: $29.95 Editor, assembler, and monitor using INTEL 8080 mnemonics.
RSL-1: 14.95 Draw patterns, then play Conway's LIFE in machine language.
LST-1 : 8.00 A disassembled listing of LEVEL-1 BASIC with some comments.

+ SMALL SYSTEM SOFTWARE * P.O. BOX 366 * NEWBURY PARK, CALIF. 91320 *

DATA TERMINAL EQUIPMENT — FROM MICROMAIL

some ig 120 *795.°°

• RS 232C, upper/lower case, full
ASCII

• Numeric keypad, protected fields

• Cursor keys plus addressable cur-
sor

• Auxiliary extension port

LA34 DECwriter IV

*1,1 99. 00

• Upper/lower case, 9x7 dot matrix

• 10, 12, 13.2, 16.5 characters/inch

• 2, 3, 4, 6, 8 or 12 lines/inch

• 22”W x 7”H x 15Vfc”D, 25 lbs.

• 110 or 300 baud, RS 232C serial
ASCII

• Friction feed, paper width to 15”

SOROC IQ 140 $1,250.°°

• RS 232C and 20mA current loop

• Extensive editing features

• 25th line terminal status display

• 16 function keys (32 with shift)

New

from DIABLO

DIABL0 1640 $2,690.°°
Receive-only $2,331.°°

High-quality daisywheel printing at
45 cps.

DIABLO 1650 $ 2,779.°°
Receive-only $2,419.°°

Metal daisywheel printing at 40 cps.

T.l. 810 printer $ 1 ,695.°°

• Includes upper/lower case

• 150 characters per second

• RS 232C serial interface

• Adjustable forms tractor

NEC Spinwriter

Call or write for prices

To Order: Send certified check (personal or company checks require
two weeks to clear) including handling* and 6% sales tax if delivered
within California.

‘Handling: Less than $2,000, add 2%; over $2,000, add 1%. Everything
shipped freight collect in factory cartons with manufacturer’s warranty.

i: MICRQMfllL

MICROMAIL • BOX 3297 • SANTA ANA, CA 92703
(714) 731-4338 ^M73

1 82 Microcomputing, October 1979

#••••*

Mm..

Mm.<

Mm«>

#••••

••••*-

##••••

Mm*.

#•••-

#•••*

#•••-

••••-

M««*.

Mm»

Mm*.

#•••«*

•m*.

|#M*.

!•••*.

MCM 7001 L— 3.29
MC 6820—5.00
MC 6800—9.99
MC 68B21— 9.99
MC 6810—5.00
MC 8257—6.99
MC 4027N— 25 @
8223—2.00
TM8 4050—3.00
TM5 4060—3.00
2516—3.99
6820—4.99
TMS 4024—64.99
Intel— 2716 @ $39.95
T.I.— 2532 @ 690.00
IM.S. — 21L02-4 @ 8 for 67.92
LM317T @ 81.99 each

Fairchild 78H05Kc, 5 VDC @ 5 amps
regulators $4.29 ea.

Standard Power Supplies, 5 VDC, 12
amps, new $59.95 ea.

2708 EPROMs @ $7.25 ea.

4.99 each MC1488 , s MC1489>s @ $1.00 ea.

Send for free catalog!

✓ S101 Semiconductor Surplus
2822 North 32nd St.,
Unit 1

Phoenix, Az 85008
602-956-9423

Write or phone in your order
today

$2.00 minimum shipping, UPS + .35 insurance per $100.00

•••#

FAIRCHILD RED LED LAMPS

#FLV5057 Medium Size Clear Case RED EMITTING These are not
retested off-spec units as sold by some of our competition These are
factory prime, first quality, new units

10 FOR $ 1 19

50 FOR $ 4 95

WE BOUGHT 250,000 PCS.”

LAB-BENCH VARIABLE POWER SUPPLY KIT

5 to 20 VDC at 1 AMP. Short circuit protected by current
limit. Uses 1C regulator and 10 AMP Power Darlington.
Very good regulation and low ripple. Kit includes PC
Board, all parts, large heatsink and shielded transformer.
50 MV. TYP. Regulation.

$15.99 KIT

MILITARY TIME FORMAT!

NATIONAL SEMICONDUCTOR

JUMBO CLOCK MODULE

MA1008D
BRAND NEW!

$795

REG. *9.95

ZULU

50% OFF SALE!

PERFECT FOR USE
WITH A TIMEBASE.

FEATURES:

* FOUR JUMBO T INCH lFD DISPLAYS

* 24 HR REAL TIME FORMAT

* 24 HR ALARM SIGNAL OUTPUT

* 50 OR 60 Hz OPERATION

* LED BRIGHTNESS CONTROL

* POWER FAILURE INDICATOR

* SLEEP & SNOOZE TIMERS

* DIRECT LED DRIVE (LOW RFI)

* COMES WITH FULL DATA

COMPARE AT UP TO TWICE
OUR PRICE!

MANUFACTURER S CLOSEOUT!

16K DYNAMIC RAM CHIP

WORKS IN TRS-80 OR APPLE II

16K X 1 Bits 16 Pin Package Same as Mostek 41 16-4 250 NS access 410 NS cycle
time Our best price yet for this state of the art RAM 32K and 64K RAM boards
using this chip are readily available These are new. fully guaranteed devices by a
major mfg VERY LIMITED STOCK!

“magazine special” — 8 For $79.50

CLOCK MODULE OPTIONS
MA1008 A and D MA1013

Switches and pot for all options:

Includes:

5 push buttons
1 toggle

1 10K pot $2.50

Alarm Parts (including high impedence
transducer) Much more efficient than a
speaker $1.50

Transducer only (unbelievably loud!) $1.10

TOSHIBA POWER AUDIO AMP

5.8 Watt RMS Typical Output. 50 to
30,000 HZ +3 DB. For CB’s, tape
decks, PA’s. etc. Works off of a single
supply voltage from 10.5 tc 1 8 VDC.
10 Pin plastic DIP with special built in
heat sink tab. Perfect for use on
12VDC. With Data. s 3.99 each

NATIONAL SEMICONDUCTOR NEW*

CAR CLOCK MODULE - #MA6008

$099

each

INCLUDES CRYSTAL TIMEBASE!
WORKS ON 12 VDC!

Originally used by HYGAIN to indicate time and
channel on an expensive C.B. Mini size, self
contained module. Not a Kit. Four digits plus
flashing indicator for seconds. Includes MM5369
and 3.58 MHZ crystal forsuperaccuratetimebase.
With hookup data.

MFGR s CLOSEOUT
LIMITED QTY

SONY 23 WATT AUDIO AMP MODULE

#STK-054. 23 WATTS SUPER CLEAN AUDIO. 20 HZ TO
100 KHZ + 2 DB. HYBRID, SILICON, SELF-
CONTAINED MODULE. ONLY W x 2% IN. WITH DATA.
COMPARE AT UP TO TWICE OUR PRICE! $ 8" each

*8" EACH

LED BAR GRAPH AND ANALOG METER DRIVER

New from National Semi. #LM3914. Drives 10 LED directly
for making bar graphs, audio power meters, analog meters,
LED oscilloscopes, etc. Units can be stacked for more
LED’s. A super versatile and truly remarkable 1C. Just out:

SPECIAL PRICE: $3.99 INCLUDES 12 Page Spec. Sheet

Digital Research: Parts

(OF TEXAS)

P. O. BOX 401247 GARLAND, TEXAS 75040 • (214) 271-2461

TERMS: Add 50$ postage, we pay balance. Orders under
$15 add 75$ handling. No C O D. We accept Visa, Master-
charge, and American Express cards. T ex. Res. add 5% Tax.
Foreign orders (except Canada) add 20% P & H. 90 Day
Money Back Guarantee on all items.

v* Reader Service— see page 227

Microcomputing, October 1979 1 83

EXTRA SPECIAL

Prices & Delivery

PRINTERS

HEATHKIT LINE PRINTER wh- 14 lAssml $ 825.00

CENTRONICS PRINTER *779 w/tractors & paper tray $ 995.00

TEXAS INSTRUMENTS PRINTER *810 (Up. & low. case) $1689.00

TERMINALS

INTERTUBE II BY INTERTEC $ 777.00

(Terminal) Z-80 controlled, 80 Char, by 24 lines, 128 upper and
lower case, ASCII Char., graphic symbols, reversible video, half
intensity video, special 25th display (status) line, 12" screen,
operating mode: conversational, message, page, Char, insert/
delete, line insert/ delete, half or full duplex, keyboard with 18
key numeric pad, full cursor control, RS232 and 20/60 Ma loop
auxiliary printer port, 75-9600 baud and a lot more special
r features all software controlled, no little mini-dip switches
to bother with.

LEEDEX VIDEO 100 MONITOR $ 138.00

NOVATION CAT ACOUSTICAL MODEM (300 baud) . . . $ 185.00

DISK DRIVES

MEMOREX 5508" Disk Drive Single or Double Density $435.00

6' Cable for two drives $ 25.00

Connectors for power supply (2 sets) $ 4.50

Power Supply $ 98.00

TARBELL DISK CONTROLLER BOARD (Kit) $179.00

PERTEC 5V«" disk drives for TRS-80 (Flippy Disk) $359.00

This drive gives you 40 tracks of storage versus the 35 track
^Radio Shack drive. The Pertec drive also has the flippy
disk feature. When you have filled one side of the diskette,
Bf lip it over and use the other side.

■ Cable $ 29.50

lTRS-80 New Dos Plus from Apparat drives 40 tracks $ 65.00

DISKETTES - VERBATIM 5'A" soft sector (TRS-80) Box of 10 $ 28.50
8" Soft sector - FD 1000 Box of 10 $ 38.50

COMPUTERS

TEXAS INSTRUMENTS 99/4 HOME COMPUTER $1095.00

CPU - The powerful 9900 16 bit microprocessor with 256 byte
scratch pad RAM. MEMORY - Total 72K bytes of ROM & RAM,
external ROM memory - (Solid state software command mo-
dules) up to 30K bytes each, 16K user RAM. KEYBOARD - 40
key, full travel, overlay for second functions. MUSIC & SOUND -
5 octives, 3 simultaneous tones plus noice generator. DISPLAY -
13" color monitor. GRAPHICS 16 colors high resolution
192 x 256, you can define your own characters, create
animated displays, charts, graphs and more.
Built-in software - 14K byte BASIC interpreter
13 digit, floating point, internal graphics language
interpreter, equation calculator & internal 4.4K
byte monitor, recorder interface. PERIPHERALS re-
mote controls, solid state speech synthesizer, RS-232 interface.

CROMEMCO

Z-2 (Assm) $ 845.00

Z-2D (Assm) For rack mounting, 4MZ Z-80, Floppy Disk Con-
troller, Mini-Floppy Disk Drive $1779.00

Z-3 (Assm) 4MZ - Z-80, Dual 8” Drives, 32K RAM, Printer

and RS-232 Interface $4989.00

Cobol, Fortran, Assmb., DBM, & other Cromemco software. . . $ 86.00

TUART (Kit) $176.00 TUART (Assm) $255.00

CALL US FOR OTHER CROMEMCO DISCOUNTS

SUPERBRAIN $2845.00

Superbrain The most cost effective machine on the market
today. Intertec has combined their excellent video terminal with
a sophisticated Z-80 computer and has come up with a totally
integrated package. This beauty includes a 4MZ Z-80 computer
system, 2 double density Mini-Floppies with 320K of disk storage,
64K of RAM memory, CP/M disk operating system with
utilities, and a complete 80 character X24 line video smart ter-
minal. This machine boasts two Z-80 processors to handle pro-
cessing & I/O. A serial and parallel interface for the I/O is

included. A S-100 edge connector is provided, so upgrading to

10-300 MB hard disks is available. If you need more info, call us.

EXIDY SORCERER W/16K $1035.00

W/32K $1135.00

GODBOUT UNKITS

16K $249.00 32K $498.00 I/O Board $184.00

— - jH Checks, money orders accepted

Add $2.50 freight charges on orders under 10 lbs. |ma 5 tercharge]j
mmm Over 10 lbs. F.O.B. Cleveland

QUASAR DATA PRODUCTS

25151 Mitchell Dr., No.Olmsted, Ohio 44070(216)779-9387

the ULTIMATE in

CHEAP VIDEO

BOOK & KIT
ONLY $42.95

Don Lancaster's "Cheap Video ’’concept allows almost
unlimited options, including:

* Scrolling- Full performance cursor.

* Line/Character formats of 16/32, 24/80, 32/64....
or almost anything.

* Graphics -up to 256 X 256 B&W; 96 X 128 COLOR

C requires low-cost option modules )

* Works with 6502 , 6800 and other micros.

SPECIAL OFFER: Buy the Kit Cupper case alpha-
numeric option included! & get the Book at 1/2 price.

^ P9 BtiA ELECTRONICS, DEPT. K . 1020 W. WILSHIRE BLVO. OKLAHOMA CITY. OK 73116

! I’m Sold. PLEASE RUSH C ) SEND FREE CATALOG

C ) TVT-6 5/g Kit & Cheap Video Cookbook $42.95
( ) TVT -6 5/8 Kit only (book required for assembly) -$39.95

name:

address.

city: state: - zip:

I RiA ELECTRONICS. DIPT 1 0K. 1020 WILSHIRE BLVD.. OKLAHOMA CITY. OK 73116

“ A COMPUTER TERMINAL ^
WITH PROFESSIONAL TYPE FONT

• operates with and without echo for greater flexibility,
does not require software to be rewritten

• easy to operate

• 50 to 150 BAUD printing speed STD — other
speeds available (at extra cost)

• RS 232 Serial or current loop interface

• custom designed micro-processor interface allows

— RS 232 interface

— current loop interface

— echo or no echo operation

— capable of generating all 128 ASCII characters

• can be used off line as a typewriter, prints upper
and lower case

• any code system operation available with up to
256 permutations (at extra cost)

Terms: Check with Order or Visa/Master Charge Account No.
$35.00 Shipping & Handling Fee

1 -1-1

N.B. Industries, Inc. ^N 26

.1 m r\

610 W. Olney Avenue

1 k ■

Philadelphia, PA 19120

- * L ^ 1

215-224-9990

1 84 Microcomputing, October 1979

t^Q9

JPC PRODUCTS FOR

6800

COMPUTERS

16 CHANNEL A/D BOARD

• 8 BIT DATA

• SOFTWARE CONTROLLED GAIN

• 3300 SAMPLES PER SECOND

• ± 0.7% ACCURACY

COMPLETE KIT: AD-16 $ 69.95

Terms: Cash, MC or Visa; Shipping Er Handling $2.00

is J 12 Order Phone (505) 294-4623
P.O. Box 5615
^JPC products**"»^ Albuquerque, N.M. 87185

You don’t have to buy it
just for the low price.

realsofr^Rf^ R ^^!l

4200 Wisconsin Ave. N. W. Washington D.C. 20016

You can buy
|t for the
quality, too!

' f*j

If you’ve been looking
for a less expensive floppy
disc drive, but not wanting to
sacrifice quality - your search is over!

You get both in the Remex RFD1000B! For
only $395 look at what you get: ■ 8” Floppy
Drive ■ Single or Double Density ■ Hard or
Soft Sectoring ■ Media Protection Feature ■

Single Density Data Separator ■ 90 Day Fac-
tory Warranty

AVAILABLE OPTIONS

□ Door Lock, $20 □ Connectors, $10

□ Write-Protect, $20 n* n terface Manual, $2

REMEX RFD1000B

VOLUME DISCOUNTS AVAILABLE

SIRIUS SYSTEMS, P 0 Box 9748. Knoxville. TN . 37920

Phone Orders accepted 9AM-7PM (E S T ) 615/577-1072

^S113

NAME.

□ Check □ Money Order DC.O 0. □ MC QVISA □ AE

CARD #_

ADDRESS _

EXPIRATION DATE-

CITY-

STATE .

. ZIP CARDHOLDERS SIGNATURE-

Add $7 00 per Drive for Shipping/Handling Tennessee residents add 6% sales tax Foreign orders
j^add 10% (payment in U S currency only)

ATERM

from Acorn Software by Sti bolt
The ASCII terminal program with the features
you need and want: truly full duplex,

completely compatible with Radio Shack's
RS-232, feed to line printer feature, all 128
ASCII characters from keyboard, support of
lower case if modification made, and BELL sound
on AUX line from computer. You set baud rate,
parity, word length, and number of stop bits
receiving. More features than similar program
selling for more than twice the price.

16k, Level II with modem. $19.95

SYSTEM SAVERS

from Acorn Software by Sti bolt
If you ever use the SYSTEM command you can use
this two program package. With FLEXL you can
make copies of your own SYSTEM format tapes or
use it to make backup copies of any hard to
load tapes. It can also identify the file name
of any system tape. TDISK will move any SYSTEM
tape onto disk. Unlike similar programs, it
will work with non-conti guous tape formats.
BONUS: Instructions show how to load

MicroChess 1.5 onto disk.

16k, Level II $14.95

If your computer likes programs, you will
like us. We carry more programs for the
Radio Shack TRS-80 computer than anyone.
We are dealers for over thirty different
companies and we continuously search for
exciting, new programs.

TRS-80 You may have noticed our change of name.::
Formerly Computer Cablevision, we have;:;
just moved into our new store in I
Washington, D.C. We have not only TRS-80 1
software, but a variety of equipment.
Please visit.

a trademark of

Tandy Corporation

?„ d i

..venture

»y Scott Adams

Inspired by its namesake on larger computers,
these programs are not mastered in an hour.
Interest is maintained as you wander through
your Adventure using commands in English like
"Kill Dragon." Games in progress can be saved
to cassette (or disk). Already a classic in
the Star Trek and Space War tradition,
different adventures for 16k, Level II
Adventureland $14.95

Pirates Adventure $14.95

Mission Impossible Adventure $14.95
Special diskette with all three $39.95

1 fsj E W ! V^ocbo Castle $14.95
\ Count Dracula $14.95

!□□□□□□□□□□□□□□□□□□□□□□□□□□□□□□!

!□ YES. please send these TRS-80 programs
title

price

postage:
total :

TTW

address :
city, state
& code

a MASTERCHARGE
Q VISA

card number:
signature:

me bank code:
exp date:

iS Reader Service— see page 227

Microcomputing, October 1979 1 85

Have we brewed
up a deal for
You!

APPLE I1 16 k

$ 1195.

ADDITIONAL 32-K MEMORY*
WITH EACH APPLE FOR ONLY

* 99 .

COMPUTER CORNER

OF NEW JERSEY
439 RT. 23 POMPTON PLAINS, N.J. 07444

PET 2001 i6 K

s 995.

Cassette Unit for above $95.00

FEATURES INCLUDE:

• 16*K Bytes RAM User Memory

• 14-K ROM Operating System
(including a Machine Language Monitor)
Full Size Business Keyboard - U/lc
and 64 Graphics Characters
9 inch CRT

• 8-K ROM Expansion Sockets

• File Management in Operating Systems

PRIME TESTED MEMORY CHIPS

VISA & MASTER CHARGE ACCEPTED

CALL TODAY

(2oi) 835-7080

^softwarc* %

from RAINBOW

PIE TEXT EDITOR Machine language, cursor-based text editor
for 16K Apple.

• Features format capabilities of most text editors.

• All commands are control characters.

• Enables you to define your own function commands.

Order PIE on cassette: $19.95 on diskette $24.95

HIGH RESOLUTION CHARACTER GENERATOR Machine lan-
guage program for 16K Apple.

• Define your own character set and graphic shapes.

• Complete English upper/lower case character set.

• Complete Greek Alphabet with upper/lower character set.

• Scroll, vary window size, invert characters, switch back and
forth between two character sets.

Order Hi-Res Char. Gen. on Diskette $19.95

FORTE Music Interpreter in Machine Language for 16K Apple.

• Handles six voices. •Single step capability.

• Full editing features. •Trace line numbers or notes.

• Save songs on cassette or diskette.

Order FORTE on Cassette . $19.95

APPLE Monitor PEELED Everything you wanted to know about
the Apple Monitor but couldn't figure out. User-written manual in

plain English clears your confusion $9.95

Call or write today for your FREE Apple Software Catalog. B/A
and Mastercharge accepted. Sorry, no CODs. Add $1.25 Shipping &
Handling. California residents add 6% sales tax. We ship promptly
on receipt of your ppd. order. Order from:

RAINBOW COMPUTING INC.

Garden Plaza Shopping Center, Dept. 9KM
9719 Reseda Blvd., Northridge, CA 91324

Telephone (213) 349-5560

is C64

AVAILABLE NOW!

M Q = QUALITY”

TRIPLE A-> D CONVERTERS $36 95

DUAL AIR TEMPERATURE SENSORS 26. 95

POWER SUPPLY & DUAL SOCKETS 29 95

DUAL PHOTO DETECTORS 27 95

MULTIPLIER, VOLTAGE-CONTROLLED

AMPLIFIER COMBINATION 43 95

PEAK-SENSE & HOLD/SAMPLE

AND HOLD 28 95

DUAL INSTRUMENTATION

AMPLIFIERS 24 95

LOG & ANTI-LOG COMBINATION 40 95

SOCKET/MOUNTING BOARD 8 95

QK-100

QK-101

QK-103

QK-105

QK-110

QK-112

QK-122

"" most kits offer stand-alone application ability

P.O. BOX 35879 TUCSON, ARIZONA 85740

(602) 299-9831 ^Qio

dealer

inquiries

* welcome

a division of j.r. conwell corporation

1 86 Microcomputing, October 1979

• PET • PET • PET • PET • PET • PET • PET • PET • PET • PET • PET • PET • PET • PET • PET • PET • PET • PET •

PET • PET • PET • PET • PET • PET • PET • PET • PET • PET • PET • PET • PET • PET

These programs are special purpose data base management systems They all can:

• Sort numeric or string fields

• Select based on numeric or string (=)

• Select based on substring match

• Select based on range of entry number

Prices: $9.90 each for programs using cassette storage for data
$12.95 each using sequential floppy disk storage for data.
$5.95 each for instruction manual, approximately 40 pages.
Add $1 50 for shipping and handling.

TIS

P.O. Box 921, Dept. KB
Loa Alamos, NM 87544

Money back guarantee

^T41

PET is a trademark of Commodore Business Machines

PET • PET • PET • PET • PET • PET • PET • PET • PET • PET • PET • PET • PET • PET

r "THE"

TRS-80 Users Journal
THE 80-U.S. JOURNAL

ANYTHING you can do on (or to) Level I,
Level II or TRSDOS is covered in detail by
THE JOURNAL. (We have been doing it with
regularity since September, 1978!)
Published bi-monthly; subscriptions are
$16.00/1 year, $31.00/2 years, $45.00/3 years
in the U.S.; $20.00/1 year, $39.00/2 years,
$55.00/3 years in Canada (First class mail)
$24.00/1 year, $47.00/2 years, $68.00/3 years
all other. (Foreign sent Airmail). MC/Visa
O.K. - call (206) 759-9642 or send check or
money order to:

The 80-U.S. JOURNAL
PO Box 7112

Tacoma, Washington 98407

U* E37

It your local dealer doesn’t have it, send $3.00 for a
current sample issue!) ^

TO ORDER CALL TOLL FREE 800-223-7318

COMPUTER FACTORY ■ COMPUTER FACTORY

PET BUSINESS SYSTEM

PET 2001 -16/32K

Features Include;

DUAL DRIVE FLOPPY DISK 2040

— \ The Dual Onve Floppy

rtd Mieen memory »C*» bu*H the <J>8fc unit
i me rc i compiler _ _ . . ,

wwcmrou*. Features Include:

TRACTOR FEED PRINTER 2022

Features Include:

Model 2023 (Friction Feed) - $849
$995 (Next day delivery available.)

FULL SYSTEM NOW IN STOCK FOR IMMEDIATE DELIVERY!

SUPER WORD PROCESSING SYSTEM

$2395 complete JESTS?*
with software * T « I>n - 0n '

fM.r>9 s,»»m .» ,n M0? nn,»tw<e on If* pngn Up nnn dm KHn uiolling mi«

TO ORDER CALL TOLL FREE 800-223-7318 (46thSt)

fV^IV/IDI ITCD CAf^TY^DV 485 Lexington Avenue 750 Third Avenue New York. N.Y. 10017
I I ie OV^IVirU I cn rHU I un I (212) 687-5001 (212) PET-2001 Foreign order desk Telex 640055

FINALLY

I TEXAS
INSTRUMENTSTI-99/4
Home Computer

I Many Peripherals. Coming soonl

me W!

APPLE II PLUs"'""ONLY$1 1 95

BASIC in RC

Features Include:

NEW 0 C. Hayes MICROMODEM II

Over 1000 software,
tapes, books, disks L
on display.

Come In and brouse.

SOUNOWARE

P only $379
NEW Mountain Hardware SUPERTALKER

SUPE&RAIN

INTE3TEC
DATA
SYSTEMS

ONLY

$2995

only $279

SPECIAL

12” Video Monitor
for SORCERER
I $299 value)

ONLY

125 with 8K unit
95 with 16K unit
65 with 32K unit

RADIO SHACK • PET • SORCERER •
APPLE • COMPUCOLOR • ETC.

ftiELNOW ,N

"stocki

PRINTERS • PRINTERS • PRINTERS

Tho COMPUTfA FACTORY 5 exte*.s.*<i
8Deci*«tignK The 1 foiling printers war

CEWTPOFRCS 779 .

’ taendcom too ...

* TRENDCOM KC

integral data
< DlAGLO. Xb.RCX .
COMPFIINT

. 795 1

2fl95|

FREE

Parallel $995

Serial SUMS ^6

TO ORDER CALL TOLL FREE 800-223-7318

The COMPUTER FACTORY,

LLOUU-aO-/JIO (46lh Sti)

485 Lexington Avenue 750 Third Avenue New York. N.Y. 10017
(212) 687-5001 (212) PET-2001 Foreign order desk - Telex 640U55

v* Reader Service— see page 227

Microcomputing, October 1979 1 87

r r

Wasatch delivers quality system components from stock

Assem. /Tested

• 4K x 8 RAM $89.95

• 2K/4K x 8 PROM

• 8-SLOT MOTHER 50.00

• 80 LINE DIGITAL I/O

Kit PCB

$79.95 $22.50

79.95/129.95 22.50

40.00 20.00

59.95 20.00

New 5V system components under development

• 8Kx 8 EPROM (2716)

• 16/32 Channel, 8 Bit A D

• 4 Channel, 8 Bit D-A

Wasatch also delivers prime semiconductor
memory at reasonable price, in addition focus
4K ram tom design services. ^W13

SEND CHECK OR MONEY ORDER

WASATCH SEMICONDUCTOR PRODUCTS

25 South 300 East • Suite 215 • Salt Lake City. Utah 84111
For orders under $25 . add $2 shipping & handling / Utah residents add 5 sales tax

Radio/baeK

Authorized Sales Center

1 117 CONWAY MISSION , TEXAS 78572

( 512 ) 581-2765

iS R34

NO TAXES on out-of-state shipments.

FREE Surface delivery available in the U.S.
WARRANTIES will be honored by your local
Radio Shack® store.

on ALL Computers, Peripherals, Software, and ALL other fine Radio
Shack® products.

MAKE YOUR TRS-80 A 3-SPEED

This simple addition allows either normal operation, a 50% increase, or a 50%
decrease in CPU speed. Unlike other speed mods, this one may be changed AT ANY
TIME without interrupting program execution. This is critical in machine language
programs where there’s no software access. Shortens calculations, sorts, and
CLOAD and CSAVE times. The low speed simplifies de-bugging, slows a Level II
LIST, and ELIMINATES KEY-BOUNCE without software overhead. Fits inside the
keyboard unit with only 4 easily accessible connections, and is easily removed if the
computer ever needs service. The Mumford Micro 3-speed kit has been field proven
by its many users and complete satisfaction is guaranteed. Kit includes all parts and
clearly illustrated instructions for $24.95. Fully assembled and tested $29.95

DUPLICATE SYSTEM TAPES WITH “CLONE”

This machine language program makes duplicate copies of ANY tape written for
Level II. They may be SYSTEM tapes (continuous or not) or data lists. It is not
necessary to know the file name or where it loads in memory, and there is no chance
of system co-residency. The file name, entry point, and every byte (in ASCII format)
are displayed on the video screen. Data may be modified before copy is produced.
CLONE $16.95

RAM TEST FOR LEVEL II

This machine language program tests memory chips for open or shorted address or
data lines as well as intermittents. It tests each BIT for validity and each BYTE in the
execution of an actual instruction as in real program execution. Bad addresses are
displayed along with the bad data and proper data. One complete test of 48K takes
just 14 seconds. Also includes a test for errors induced by power line glitches from
external equipment. RAMTEST $9.95

PROGRAM INDEX FOR DISK BASIC

Assemble an alphabetized index of your entire program library from disk
directories. Program names and free space are read automatically (need not be
typed in) and may be alphabetized by disk or program. The list may also be searched
for any disk, program, or extension; disks or programs added or deleted; and the
whole list or any part sent to the printer. Finally, the list itself may be stored on disk
for future access and update. One drive and 32K required. INDEX $19.95

EDIT BASIC PROGRAMS WITH ELECTRIC PENCIL

This program allows disk users to load Basic programs into the disk version of
Electric Pencil for editing. Now you can edit line numbers, move program segments,
and search for the occurance of any group of characters. PENPATCH $9.95

INCLUDE 75C POSTAGE — CALIFORNIA RESIDENTS ADD 6% SALES TAX

MUMFORD MICRO SYSTEMS

BOX 435-C SUMMERLAND, CALIFORNIA 93067
^ M87 (805)969-4557

ENCLOSURE

POWER SUPPLY

SPECIFICATIONS:

INPUT: 110/220 VAC 50/60 Hz
OUTPUT: ♦ 5V 0 5A
+ 24V 0t 1A

GROUNDED THREE-WIRE LINE CORD
ON/OFF SWITCH WITH PILOT LIGHT
Enclosure has room lor the AIM and one
additional board: MEMORY PLUS or VIDEO PLUS

AIM PLUS: $100 00 AIM and AIM PLUS: $4750°

ikIJMUiiY m F0R

AIM/SYM/KIM
8K STATIC RAM P i°* R
Sockets for 8K Eprom
6522 1/0 Port

ON BOARD REGULATORS

EPROM

PROGRAMMER

MEMORY PLUS: $200.00 fully assembled and tested

1 88 Microcomputing, October 1979

Put Yourself in Control with the

-s = RPPXJEIHROTTLE

That's right! The fisPPlETHROTTLE will turn
your game paddles into a speed controller.

By simply pushing a button, you can stop
your computer for as long as you want.

Release the button, and your computer
enters a slow-motion mode with one
paddle controlling the speed. And if that
isn't enough, look at these additional
features:

• Plugs into any slot

• Works with machine language, Integer
BASIC, and Applesoft

• Normal • slow - stop

• Gse to LIST, TRACE, RGN, etc.

• NO SOFTWARE to load

• Gnveil program secrets ^=APPLE THRO TTL E

And there's more! No more multiple LIST commands to view small program
sections. With the APPLE THROTTLE, you'll be able to list or trace long
programs while watching your program flow in slow-motion. So get in control
with the APPLE 7>y/?0 TTLE and order yours today!

$89.95

APPLETIME, a Real Time Clock
for the Apple II. Plugs directly into any
slot and keeps time even when
computer is off. Features 12/24
Hour, BCD/ ASCII data format, and
AC/Crystal time base sel ection.
Includes software examples for
machine language and BASIC pro-
grams. Completely assembled and
tested.

APT-1 Real Time Clock $79.95

PROTOBOARD, with over 1300
holes on 0.1 centers for designing
your own circuits.

APB-1 Protoboard .... $17.95

VERBATIM 5Y4" DISKETTES

Soft-Sector Box of 10 . . . $34.50
(plastic file case included)

west side electronics

P.O. Box 636, Chatsworth, CA 9131 1

We pay all shipping in Continental U.S.A.
Others add 10%. California residents add 6% tax

=-|UEW TRS-80 CASSETTES
SOFTWARE* & HARDWARE

MORE GAMES

GT-3 Chicken — A challenging game with sound effects! Hear engine idling and
revving sounds. Approaching a wall at high speed, you must hit your brakes
before you smash against the wall! Speed varies randomly. The player who comes
closest to the wall without crashing wins. (Available in Level II only.) Price:
$ 10.00

GT-5 Moving Maze— If you don’t have a lot of patience, then you had better not
try this game. You must get from one side of the maze to the other side through
moving gateways. A usable gateway may or may not appear soon, but when one
does you had better be ready to react. Failure to react fast enough can cause you
to be slammed out of existence! (Available in Level II only.) Price: $ 1 0.00
Note: Sound effects games require no extra wiring or interfacing.

HARDWARE

Finally in stock again! Back by popular demand!

HW- 1 Computer and Peripheral Power Control Center— (Are you gonna love this!)

1) Turns on computer, video monitor, tape recorder and/or various peripherals
with the flick of a single switch! NO REWIRING OR EXTRAS NECESSARY! |ust plug
everything into this unit. 2) No need to have your video monitor near a wall
socket! Power center has built-in polarized receptacles which will accept the
polarized video monitor plug, though the unit itself will plug into any unpolarized
extension cord socket or polarized socket. 3) Power everything from a single wall
socket since unit needs only one wall or extension cord socket! 4) Built-in fuse cir-
cuit protects your TRS-80 power supply! 5) Red L.E.D. indicator glows when
system is powered up. 6) Attractive unit takes up very little space (3 in. x 6 in. x I
in.). 7) Ready to go as soon as you get it. |ust plug it in. Even great for other makes *
of computer!

If this unit is not everything we claim, just send it back for a full refund. Price: only
$ 12.00

c.o.d.

accepted

•We do not sell through dealers and stores because our special antiplagiarisr
system will only work effectively with an exclusively mail order market I
order to encourage people to go through the extra inconvenience of ma
order. Computrex will continue to offer software that is unique
V exclusively from us

Send S.A.S.E. to receive product list faster. Phone #: 1-800-472-8185. Refer to
previous issues of this magazine for other available products.

Compuirex

PO Box 536 Inman SC 29349

PET and TRS-80
“LOAD and GO” SOFTWARE
PRE-RECORDED
BUSINESS PROGRAMS

No Programming Experience Required!

♦GENERAL LEDGER 66 Accounts. For home, businesses,
sole proprietorships, small corpora-
tions. $29.95 plus $1.50 S & H (8K
min. user memory)

♦CHECKING ACCOUNT For personal bank accounts. $23.95
plus $1.50 S & H. (8K min. user
memory)

♦RENT ACCOUNTS Records of Rental Property $29.95
plus $1.50 S&H.

*LEGAL DIARY For attorneys (client accounts).

$23.95 plus $1.50 S&H.

♦TRUST ACCOUNTS For attorneys (client accounts).

$23.95 plus $1.50 S&H.

Send check, money order or charges (VISA or MASTER CHARGE,
include charge number and exp. date)

♦Specify which computer is used*

1314 South King Street, Suite 1156
Honolulu, Hawaii 96814

♦Since 1977 — Over 3,000 programs in use*

tS C81

The Fastest, Most Cost-Effective North Star
Business Software Available . . . Period!

We offer features that no one else has, at any price. For example:

GENERAL LEDGER 2.4

* Uses standard double entry accounting methods.

* Uses our Skip Sequential " file structure for fast posting and
efficient use of disk space (see May, 1979 KILOBAUD,
page 16).

* Direct cursor control for the SOL, SOROC, ADM-3 and
ADDS-100 video systems. (Standard version for all other
video systems.)

* Custom Chart of Accounts with full editing. (A system with
1 6K of user memory will support over 200 accounts.)

* Posting by account name, number, OR both.

* Printer output routines for Income Statement, Balance
Sheet, Data files and other reports.

* Can be used by CPA's on a "one-disk-per-client" basis
(specify CPA version when ordering).

* All programs are parameter-driven to avoid repetitive inputs.

* Operator's manual designed for the user with no computer
experience.

* A total of 18 programs for the ultimate in user flexibility.

* Price; only $99.95!

We also have A/R, A/P, Payroll and the most comprehensive
statistics package available anywhere. All programs use North
Star Release 4 or 5 DOS and BASIC, single or double density.
Operator's manuals available for $5.00 (credited towards
purchase). Please specify video system when ordering.

master charge | EC0S0FT *^E34

p.O. Box 68602 Indianapolis, IN 46268

Reader Sen/ice — see page 227

Microcomputing, October 1979 1 89

OUTPUT

(from page 8)

the five- and six-year-olds some-
thing, you’ll have to make it into a
game for them so they will have
fun and keep going because they
are enjoying it. Learning has tp be
fun if it is ever going to be popular.

Careers

Instant Software is still looking
for people interested in a career in
microcomputing. Someone with
extensive experience in BASIC
programming might qualify for
editor-in-chief, with the respon-
sibility for soliciting and evaluat-
ing programs. More help is re-
quired in production, purchasing,
accounting, sales, advertising and
writing. If we’re ever going to
achieve our goal of five new pro-
gram packages produced per
working day, we’re going to need a
lot more dedicated people. No
smokers, please.

DET-POURRI

(from page 20)

erating systems. Its text editor fea-
tures auto line numbering, search
commands and renumbering
capability. The $49.95 price in-
cludes a large manual with ex-
amples and a cassette ready to
LOAD and RUN. Soon Moser
will offer a graphics drawing com-
piler for use with the ASSM/TED.

Programma International

Programma International is on
the move. A few months ago I
told you to watch them. They
now are distributors for software
from PETSOFT, a major soft-
ware house in England. Program-
ma now will have more good pro-
grams to add to their already large
offerings; included will be PET-
FORTH, a high-level-language
compiler for the PET. The best
news is that Programma will dis-
tribute the final version of Mike
Richter’s sophisticated software

package, Hunt. Hunt remains on
my list of best PET programs.
I’m glad that Mike has a good
company distributing his final,
polished version. Preliminary
versions that I offered via the
PET Gazette are now replaced
by the final version. All orders
and inquiries should be made to
Programma. Orders for the pre-
liminary versions will automati-
cally, be forwarded to Program-
ma. Other Programma programs
include: Home Accounting, Math
Pack, Personal Accounting Sys-
tem and Word Processor.

Programmer’s Tool Kit

Skyles Electric Works (10301
Stonydale Dr., Cupertino CA
95014) has a ROM set that both
old- and new-PET owners should
be interested in. It adds these 11
commands to your PET BASIC:

• AUTO— Provides auto line
numbering.

• HELP — This command will
list the line in your BASIC pro-
gram where an error occurred,
and the erroneous portion is in-
dicated in reverse video.

• TRACE, STEP, OFF— Let
you see the sequence in which
your program executes in the up-
per-right corner of your screen.

• FIND — Prints lines that in-
clude the string you specify.

• RENUMBER— Now you can
renumber any BASIC program in
your PET without having to load
in a renumber program.

• APPEND — Merges program
segments.

• UNLIST

• DELETE — Deletes groups of
lines.

• DUMP— Lists all variables
with their contents.

These commands are all avail-
able as soon as you turn on your
PET. You never have to worry
about loading the programs from
tape. To order this ROM chip,
make sure to specify how you
wish to use it.

1. With the Skyles Memory Ex-
pansion system — $75.

2. With the ExpandaPET or Ex-
pandamem — $75.

3. With the old PET alone— $75.

4. With the new PET alone — $50.

5. With Sklyes Macrotea— $50.

Since these are customized, please
include your PET serial number

TfENElEET
KIUI

A specially designed SF TACTICAL BATTLE GAME for
your PET, TRS-80 or APPLE Computer.

The man called Sudden Smith watched the five blips on
his screen spread out to meet the enemy. Two freighters
converted into something like battlewagons, powerful
but slow, and three real cruisers: the most powerful group
of warships ever seen near the Promethean system — except
for the Stellar Union fleet opposing them. Everyone was
calling it Starfleet Orion, though it existed for only this
day. It was life or death, and, after the object lesson on
the planet Spring, everyone knew it.

STARFLEET ORION is a complete 2 player game system

• rule book • battle manual • cassette

• ship control sheets • program listings

Includes 2 programs, 22 space ship types, and 12 play tested
scenarios. Game mechanics are extremely simple, but play
is exciting, challenging, and rich in detail. Specify PET (8K),
TRS-80 (Level II, 16K), or APPLE II (16K& 32K) $19.95.

Ask your local dealer or send your check to:

Automated Simulations ^azi
D epartment B
P.O. Box 4232
Mountain View, CA. 94040

California residents please add 6% sales tax

190 Microcomputing, October 1979

with your request.

Merge Programs

This merging method is by Brad
Templeton. It was previously
printed in “PET User Notes,”
1-6. Jim Butterfield said we could
relate this information.

1 . Load the program you wish
to merge onto another.

2. Rewind a blank cassette. La-
bel it ASCII of program name.

3. Type in this line: OPEN 1,1,
1:CMD1:LIST [RETURN].

4. Press RECORD and PLAY
as requested.

5. After tape stops moving,
type Example 3 for old PET and
Example 4 for new PET.

You now have a tape of the

program, currently in the PET,
that can be merged with other
programs not containing the
same line numbers. It is an ASCII
listing of the program. We will re-
fer to it as ASCII Program.

Now, here is how to do the
merge. You have two programs.
One is ASCII Program; the other
is the one you wish to add ASCII
Program to. We will refer to it as
Original Program.

1 . Load Original Program into
PET.

2. Remove tape and place
ASCII Program cassette into tape
#1 and rewind it.

3. Type: OPEN1 [RETURN].

4. Press PLAY as requested
and wait for tape to stop moving.

5. Clear the screen and type
four cursor-downs: [CLR, 4

?“POKE61 1,0”:PRINT#1 :CLOSEl (RETURN]

Example 3.

?“POKE175,0”:PRINT#1 :CLOSEl [RETURN]

Example 4.

DOWN].

6. Type Example 5 for the old
PET and Example 6 for the new
PET. Do not hit RETURN.

7. Type cursor home and six
cursor-downs: [HOME, 6
DOWN].

8. Type the same line as listed
in step 6.

9. Hit RETURN.

10. Your tape will move. Even-
tually, things stop with a ? SYN-
TAX ERROR or ?OUT OF
DATA printed between the two
lines. The tape should then stop
moving. If not, simply hit the
STOP key.

11. Type: CLOSE 1 [RE-
TURN].

12. SAVE your now complete-
ly merged program.

Correspondence to: Len Lind-

say, 1929 Northport Dr., Rm. 6,
Madison WI 53704.

PRODUCTS

(from page 27)

ters on clear) that comes with each
cassette. The decals are easily and
permanently placed on the front
surface of each key on your key-
board, which readily identifies
each shorthand key function.
TSHORT loads in low memory,
thereby not interfering with
BASIC, DOS or user machine-lan-
guage routines. Price is $9.95.

Web Associates, PO Box 60T,
Monrovia CA 91016. Reader Ser-
vice number W20.

POKE61 1 , 1 :POKE525, 1 :POKE527, 13:?“(HOME]”

Example 5.

POKE175.1 :POKE 158,1 :POKE623, 13:? “[HOME]”
Example 6.

Soroc 120 $790

Soroc 140 $1260

Hazel tine 1400 $685

Hazeltine 1410 $780

Hazeltine 1500 $999

Intertube $764

Perkins- Elmer/Bantan. . $775

TRS-80 Level II

16K, exp. I/O $1199

32K, exp. I/O $1270

Sorcer-Exidy

16K system $1095

32K system $1270

Comprint 912 $529

Heath WH-14 $749

Centronic8779 $995

Dec LA36 $1345

Nec 5510 $2455

Qume Sprints/45. . . . $2999
TI 810 $1650

Cromemco

ZPU(kit)

. . . $279

Z-2(kit)

. . . $545

Z-2D(kit)

. . $1295

System 2

. . $3399

System 3

. . $4799

Multi-user basic . . .

. . . $700

24 HR. ORDER SERVICE
Ph (219) 293—4316 Mon-Sat

mo cbs x mum

P.O.Box 621 ^ M94
Bristol, IN 46507

| HANDLING: Terminals add 3% for

shipping or freight collect
| TO ORDER: Send certified check or
M.O. For personal or
business allow 2 weeks

INDIANA RESIDENTS: add 47c

FOR TRS-80' OWNERS

Programming Amateur’s Letter

THE “DO-IT-YOURSELF” SOFTWARE NEWSLETTER
LEVEL II FROM THE BOTTOM UP ... IN PLAIN ENGLISH!

BUSINESS • PERSONAL • HOBBY

THERE’S NOTHING ELSE LIKE IT!

Published monthly . . . $24. per year ... $1 for sample

□ Here’s my check for $24. Please
enter my subscription for 1 year.

Name

Address

City.

State

v* M88

THE MAIL MART

Dept. K, Box 11102
San Francisco, CA 94101

...

iS Reader Service — see page 227

Microcomputing, October 1979 191

Micro Computer Industries, Ltd.

1 532 EAST MULBERRY UNIT H

FT. COLLINS. COLO. 80524
PHONE 303-221-1955

CBM or PET Inventory Control

Cassette version, 8K PET $39.95

Disk version, 2500 items per drive with
history and data base management.
Writes purchase orders; sorts by 10 fields;
no computer experience required.

$ 100.00

Instructions $10.00 refundable with purchase

Complete system with 32K computer,
2040 disk drive, 2022 tractor printer with
inventory control $3,297.50

^M111

From time to time Kilobaud Microcomputing makes its
subscriber lists available to carefully-screened companies and
organizations whose products, services or information may be of in-
terest to you. In every case, we must approve all organizations wishing to
mail to our subscribers. In every case they receive a list of names and ad-
dresses only— no other information we may have is divulged. Each organiza-
tion may use the list only once and agrees never to make any personal or
telephone solicitations from it.

The overwhelming majority of our subscribers appreciate this controlled
use of our mailing lists— it helps them shop conveniently by mail for products and
services they need, often at substantial savings. A few people prefer their names not
be used. It is to them we address this message.

If you do not wish to be a part of this service, please complete the form
below . . . your name will not be used in this manner for any reason.

(If you asked us in the past to remove your name from our lists, there is no
need to repeat the request.) Please allow about six weeks for your request to take ef-
fect.

□ I wish to have my name removed from the list of subscribers receiving mail other
than the regular subscription to Kilobaud Microcomputing.

Mr.

Mrs

Send to: Ms. -

Please Print

Address
City

_State_

Zip_

Mail this form with your mailing label from the latest Issue (or fill out the information
as it appears on the label) to:

Kilobaud Microcomputing
Subscription Services Dept.

P.O. Box 997

______ Farmlngdale NY 11737 ______

rnrri up to * 170 in merchandise
Hitt! with the purchase of PET— CBM

item!!!

PET 16K Large Keyboard
PET 32K Large Keyboard
PET 8K

PET 2040 Dual Disk (343K)
PET 2023 Printer (pres feed)
PET 2022 Printer (trac feed)

FREE

MERCH.

$ 995 $130
$1295 $170
$ 795 $100
$1295 $170
$ 849 $110
$ 995 $130

KIM-1 $159 (Add $30 for Power Supply) SYM-1 $229.00

2114 L 450 4K Static RAM 6.95

2716 EPROM (5 Volt) 38.00

6550 RAM (for 8K PET) 1390

6502 Microprocessor Chip 9.75

6522 VIA 9 75

6520 PIA 10.50

Auto-Repeat Hardware for PET 24.50

Kite Fight - 2 player PET action game 7.95

Microchess 2.0 for PET or APPLE 17.90

PET Word Processor - Machine Language 24.00

3M "Scotch" 8" disks oai r 10/331

3M "Scotch" 5" diskettes oALt 1 0/S35

Verbatim 5" diskettes 10/$27

Cassettes (all tapes guaranteed)

Premium quality, high output lownoise in 5 screw
housing with labels:

C-10 10/5.95 50/25.00 100/48.00
C-30 10/7.00 50/30.00 100/57.00

WRITE FOR 6502 AND S-100 PRODUCT LIST m
115-B E. Stump Road

A B Computers Montgomeryville, PA 18936
(215| 699-8386

25 START-AT-HOME
COMPUTER BUSINESSES

In "Low Capital, Startup
Computer Businesses"

CONSULTING • PROGRAMMING • MICRO COMPUTER
OPPORTUNITIES • SOFTWARE PACKAGES • FREELANCE
WRITING • SEMINARS • TAPE/DISC CLEANING • FIELD
SERVICE • SYSTEMS HOUSES • LEASING • SUPPLIES •
PUBLISHING • HARDWARE DISTRIBUTORS • SALES
AGENCIES • USED COMPUTERS • FINDER’S FEES •
SCRAP COMPONENTS • AND MORE . . .

Plus — ideas on moonlighting, going
full-time, image building, revenue
building, bidding, contracts, marketing,
professionalism, and more. No career
tool like it. Order now — if not completely
satisfied, return within 30 days for full
immediate refund.

• 8V 2 x 11 ringbound • 156 pp. • $20.00

Phone Orders 901-761-9090

DATASEARCH

incorporated

4954 William Arnold Road, Dept. A. Memphis, TN 38117
Rush my copy of "Low Capital Startup Computer Businesses" at $20.

NAME/COMPANY

ADDRESS

CITY/STATE/ZIP

□ Check Enclosed □ VISA □ Master Charge
# Exp. Date

192 Microcomputing, October 1979

■ A

FORUM SOFTWARE for the

topple computer

HANGMAN- A disk based version of the famous word guessing game. The disk contains
460 words for the computer to choose from. The program allows for easy addition of user words or
addition of an entirely new file. A lot of parents put their childs spelling words into a file for their
child to enjoy and learn at the same time. There are clever lo*res graphics to make this game
enjoyable for all.

Stock #005-00481 $14.00

NAME & ADDRESS — This program has data fields for name, address, city & state, zip
code, phone number, two code fields, birth date, anniversary date and a 20 character note field.
The program is ram based and there are two versions. One for tape and one for disk. The program
will hold approximately 270 listings and can search all in less than 1 minute. The searches that it
will do are: first and last initials, all three initials, first name, last name, full name, dates, codes

and notes.

Tape Stock #005-00476 $15.00

Disk Stock #005-10502 $19.00

CATALOG PROGRAM — This program allows you to keep track of all your programs on
one disk. It allows you to choose the name of each category and you can put each program in as
many categories that you want to. It will show you a list of all categories on file and then show you a
list of all programs in any given category. When you choose a program, it will tell you which disk
that program is on. If you then install that disk, the catalog program will access a loading file which
can give you a message about the program then give you the option to continue looking through the
catalog or to load and run the program you choose by pushing the proper key, all automatically.
Stock #005-00460 $19.00

MEMORY CRUNCHER — This program will let you examine any ram or rom locations.
You can switch from a hex dump to ASCII by pushing the “H” for HEX or "A” for ASCII. You can
be looking at the dump in hex and instantly change the entire screen to ASCII by hitting the "A”.
There are provisions to allow you to change any changeable RAM location without exiting the
program. This program will make it extremely easy for you to find and change text within a basic or
machine language program including DOS.

Stock #005-11794 $10.00

Tarbell 32K RAM Memory

★S-100 BUS ★ ★300ns ★ ★STATIC MEMORY ★

★9 REGULATORS PROVIDE EXCELLENT
HEAT DISTRIBUTION ★

★ EXTENDED ADDRESSING (Bank Switching) ★

★ LOW POWER REQUIREMENT ★
★PHANTOM LINE ★

★20 PAGE OPERATING MANUAL ★

★ FULL 1-YEAR WARRANTY ★

FULLY ASSEMBLED AND TESTED $625.

SAME BOARD WITH ONLY 16K INSTALLED $390.

Add SI. 50 for shipping & handling. We pay S & H for orders over $25.00
Calif. Residents add 6% sales tax.

Our software catalog has over 200 pieces listed.

Dealer inquiries invited.

SOFTWARE AVAILABLE FOR F-8, 8080, 6800, 8085, Z-80, 6502, KIM-
1, 1802, 2650.

EPROM type is selected by a personality module which plugs into
the front of the programmer. Power requirements are 115 VAC,
50/60 HZ at 15 watts. It is supplied with a 36 inch ribbon cable for
connecting to microcomputer. Requires V/i I/O ports. Priced at
$155 with one set of software. Personality modules are shown
below.

Part No.

Programs

Price

PM-0

TMS 2708

$15.00

PM-1

2704, 2708

15.00

PM-2

2732

30.00

PM -3

TMS 2716

15.00

PM-4

TMS 2532

30.00

PM-5

TMS 2516,2716,2758

15.00

Optimal Technology, Inc.

Blue Wood 127, Earlysville, VA 22936

Phone (804) 973-5482 ^oio

Please send check or money order. No CODs or credit will be accepted on this item. Califor
nia residents please add 6% sales tax. _

*^T11

950 Dovlen Place • Suite B • Carson, Calif. 90746
(213)538-4251 (213)538-2254

Good Buys From Disks, Etc.

Verbatim 10 for $29.00
MINI DISKS or 3 for $10.00

New! Verbatim Digital Quality
Cassettes For Personal Computers

Professional quality cassettes feature leader-free, splice-
free, premium grade tape, precision engineering features.
For top performance in popular personal computers,
including Apple, PET, Heathkit, Atari and Mattel.

2 for $5.45

Mini-Disk
Protectors
Fit 3-Ring Binders

Tough, glare-proof vinyl.
Holds 2 diskettes and ID cards.

75t ea., 10 for $5.75

MasterCharge,

Visa,

Checks OK.

No COD’S.

Storage Cases

Made of durable, molded
plastic. Choice of black or beige.

Maxi Case, $4.25
Mini Case, $3.75

P.O. Box 327
Disk s, Etc. Center Valley,
Pa. 18034

»^D48

iS Reader Service— see page 227

Microcomputing, October 1979 193

HOBBY

Your one-stop mail order

California Computer Systems

Available at HOBBY WORLD

Model 2500A
S-lOO

Wire Wrap
Board

• S-100 BUS compatible

• Double sided PC board

• Plated thru holes

• Perimeter ground

• All S-100 BUS signals labeled
and numbered

• Accommodates standard size
1C sockets

• 4 to-220 regulator positions
available

• Allows either positive or neg-
ative regulators

• Dense hole configuration

. Cat No. 1600 $ 27.00

Model 2501 A
S-lOO

Solder Board

• S-100 BUS compatible

• Double sided PC board

• Plated thru holes

• Perimeter ground

• All S-100 BUS signals labeled
and numbered

• Accommodates standard size
1C sockets

• 4 to-220 regulator positions
available

• Allows either positive or neg-
ative regulators

• Dense hole configuration

. Cat No. 1604 S 27.00

| Model 2501A S-IOOI

Mother Board

• 12 slot capability

• All 12 S-100 bus connectors in-
cluded

• Low inductance inner-connect
to reduce signal noise and
crosstalk

• Active termination of all bus
lines to further reduce signal
noise and line reflections

• Distributed bypassing of all
power lines

• Solder mask both sides of
board

• Silkscreen of reference desig-
nations

• Simple strong board mounting

• Criss-cross BUS lines both
sides of board

• All holes plated thru

• Solder plated circuit area

Cat No. 1616 Kit S 90.00

LCat No. 1615 A&T $105.00 u

Model 2520A
S-lOO

Extender/

Terminator

• Active and/or dynamic term-
ination

• All power lines fused for pro-
tection

• All S-100 lines labeled and
numbered

'• Can be used as an extender
and/or terminator

• Solder mask both sides of
board

• Silkscreened reference desig-
nations

1 Cold plated fingers
^Cat No. 2520 Kit $ 37.95 A

Model 7811 A
Apple II

Arithmetic

Processor

Based on AMD AM9511 de-
vice

1 Fixed point 16 and 32 bit op-
eration

1 Floating point 32 bit operation

1 Binary data formats

1 Add, subtract, multiply, and
divide

1 Trigonometric and inverse tri-
gonometric functions

1 Square roots, logarithms, ex-
ponentiation

' Float to fixed and fixed to float
conversions

> Stack oriented operand stor-
age

» Programmed I/O data transfer

> End signal selectable interrupt

1 Supports interrupt daisy chain

1 Allows DMA daisy chain

> Power down ROM

» 256 bytes firmware (ROM) or
software (RAM) space avail-
able

:at No. 1635 $375.00

Model 7114A
Apple II

Prom Module

The 7114A PROM MODULE per
mits the addition or replacement
| of the Apple II firmware without
the physical removal of the Apple
II ROMS. This allows soft-
I ware/firmware replacement,
change, and/or patch to be made
on a ROM or BYTE BASIS. An
on-board enable/disable toggle
| switch is also available.

’ BYTE oriented program over-
lay

• Selectable prom overlay

• Power down of PROMS

• 14K PROM space available

• Uses +5 volt 2716 type proms
| • Allows use of DMA/interrupt

daisy chains
I Cat No. 1631 A&T $ 72.00

LCat No. 1630 Kit $ 62.00

Model 201 6B

s-ioo

16K Static
Memory

• Fully static operation

• Uses 2114 type static rams

• +8 VDC input at less than 2
amps

[ • Bank select available by bank
port and bank byte

• Phantom line capability

• Addressable in 4K blocks in 4K
increments

• 4K blocks can be located any-
where within 64K bank

• May be used as a 4K, 8K, 12K
or 16K memory board

• Led indicators for board/bank
active indication

• Solder mask on both sides of
I board

• Silk screen with part and refer-
ence designation

' Available fully assembled and
tested, as a kit, or as a bare
board

I Cat No.1601A Kit 450ns $285.00

Cat No.1601B Kit 200ns $340.00

Cat No.1602A A&T 450ns $330.00
L Cat No.1602B A&T 200m $305.00 j

Model 7470A
Apple II

3 3 /4 Digit BCD
A/D

Converter

The 7470 allows conversion of a
DC voltage to a BCD number for
computer monitoring and analy-
sis. Typical inputs would be DC
inputs from temperature or pres-
sure transducers.

• Selectable interrupt on end of
conversion

• 20QMS per conversion

• -4 to +4 VDC full scale

• Plus or minus .05% nonlinear-
ity

• Plus or minus 1 count quanti-
zation

• Correctible offset error

• Temperature coefficient ad-
justment

• Calibration adjustment

• Input offset adjustment

• Floating inputs

• Overange and sign indicators

• Input filter

• Power down ROM

• Supports interrupt daisy chain
I • Allows DMA daisy chain

| * 256 byte firmware (ROM) or
software (RAM) space avail-
able

[ Cat No. 1621 Kit $115.00

LCat No. 1622 A&T $135.00^

Model 2200A

Mainframe

1 S-100 compatible
1 Industrial/commercial quality
construction

• Flip-top cover

• Excellent cooling capability
12 slot capability (uses model
2501 A)

I • Input 105, 115, or 125 VAC

• Output +8 VDC, 20A + -16
VDC 4A

I • Active termination of all bus
lines

Fan and circuit breaker includ-
ed

Rugged construction
I • All parts available separately
Cat No. 1612 Kit $330.00
L Cat No. 1614 A&T $375.00 ,

Model 7440A
Apple II

■Programmable!
1 Timer Module

• Flexible external interface |
patch area for custom inter-
face applications

• Selectable prescaler on timer
3 capable of 4mhz input

• Programmable interrupts

• Readable down counter indic-
ates counts to go to time-out

• Selectable gating for frequen-
cy or pulse width comparison

• Three asynchronous external
clock and gate/trigger inputs
internally synchronized

• Three maskable outputs to
patch area

• Power down ROM

• Supports interrupt daisy chain

• Allows DMA daisy chain

• 256 byte firmware (ROM) or
software (RAM) space avail-
able

Cat No. 1617 Kit $135.00

LCat No. 1618 A&T $145,00 2

Apple II
Model 771 2A

Synchronous
Serial
Interface

• Conforms to RS-232C (config- I
uration A thru E)

• Supports half or full duplex
operation

• DTE type configuration

• Failsafe RS-232C operation

• 14 STD CLK rates 50-1 9.2K f
BAUD plus EXT CLK

• BAUD rates dip switch select-
able

• All BAUD rates crystal con-
trolled

| • Programmable interrupts from
transmitter, receiver, and error
detection logic

I • Character SYNC by one or two
SYNC codes

• Programmable SYNC code re-
gister

I • Standard synchronous signal-
ing rate per RS-269/ANSI X3.1-
1976

1 Peripheral/modem control
functions

I • Three bytes of fifo buffering
on both transmit and receive
date

1 7,8, or 9 bit transmission

I • Optional odd, even, or no par-
ity bit

• Parity, overrun, and overflow
status checks

| • Power down prom

» 256 bytes firmware (ROM) or
software (RAM) space avail-
able

1 Supports interrupt daisy chain

> Allows DMA daisy chain

LCat No. 1627 Kit $ 90.00 j

Apple II

, Model 7710A

Asynchronous
■ Serial
interface

• Parity, overrun, and framing I
error check

• Optional divide by 16 clock I
mode

• False start bit detection

• Software programmable inter- I
rupts

• Data double buffered

• One or two stop bit operation I

• Power down PROM

• 256 bytes firmware (ROM) or |
software (RAM) space avail-
able

• Supports interrupt daisy chain I

• Allows DMA daisy chain [

• 134.5 BAUD available for sel- |
ectric interface

• Conforms to RS-232C (config- I
uration A thru E)

• Supports half or full duplex |
operation

• DCR type interface

• Failsafe RS-232C operation

• 14 STD CLK rates 50-19.2K
BAUD plus EXT CLK

• BAUD rates dip switch selec-
table

• All BAUD rates crystal con-
trolled except EXT

• 8 and 9 bit transmission

• Optional even, odd, and no
parity bit

• Programmable control regis-
ter

Cat No. 1624 A&T $145.00

LCat No. 1623 Kit $ 90.00J

Model 7720A
Apple II

Parallel
Interface

| • Two bi-directional 8 bit buses
for interface to peripherals

I • Tow programmable control
registers

1 Two programmable data dir-
ection registers

1 Four individually controlled
interrupt input lines; two use-
able as peripheral control out-
puts

| • Handshake control logic for
input and output peripheral
operation

I • High impedance 3 state and
direct transistor drive pheri-
pheral lines

I • Programmable interrupts

I • CMOS drive capability on side
A peripheral lines

I • 2 TTL drive capability on all A
and B side buffers

I • Power down ROM

• Supports interrupt daisy chain

• Allows DMA daisy chain

I • 256 bytes firmware (ROM) or
software (RAM) space avail-
able ‘

I Cat No. 1633 A&T $105.00

1 Cat No. 1632 Kit $ 62.00

Model 7500A
Apple II

Wire Wrap
Board

I The 7500A is used for the
] prototyping or building of uniquel
I circuits for the Apple II
| computer.

• All bus signals labeled on I
board

• Perimeter ground

• Size: 7 inch long x 2.75 ini
high

• All holes plated thru

• Gold plated conector fingers I

Cat No. 1606 $ 19.00 [

Model 751 OA
Apple II

Solder Board

The 7510A is the same as the
7 500 A except it is designed for
soldering of circuits.

| Cat No. 1607 $ 19.00 |

Model 7590A
Apple II

Etch Board

I The 7 590 A is a two sided copper |
board which allows the actual
etching of circuits for use in the |

I Apple II computer.

I Cat No. 1608 $ 19.00

Model 7520A
Apple II

Extender

Board

The 7520A is a handy tool
when debugging or testing
modules in the Apple II.

LCat No. 1611 Kit $ 21.00i

19511 BUSINESS CENTER DRIVE

194 Microcomputing, October 1979

CALL TOLL FREE:
(800)-423-5387

CA, HI, AK:
(213) 886-9200

computer store! ^

■ i®

[apple;

rCOMPUTALKERl

SPEECH
SYNTHESIZER

The finest low cost, high quality
electronic speech synthesizer. Pro-
grammable to any language or
dialect.

^Cat No. 1916 For Apple II $490j

5y 4 »

VERBATIM
DISKETTES

Cat No. 1148
box of 10

SSM AIO

APPLE II SERIAL
& PARALLEL
INTERFACE

Interface your Apple with
printers, plotters, terminals,
modems, etc. Features one RS232
serial interface, two bi-directional
8-bit parallel ports, on board firm-
ware. With comprehensive users
manual and application notes for
interfacing with many popular
printers and terminals.

Cat No. 1918 kit $129

Cat. No. 1919 a&t $169

APPLE TALKER

Give your Apple the power of I
speech! Digitizes words and
sets up a table so that these
words can be called on under |
program control. Requires re-
corder + 2 mikes. This and
Apple Lis'ner can be used as
subroutines.

Cat No. 1691 $15.95

APPLE LIS’NER

Communicate with your Apple
via speech! Use your cassette
recorder and a mike. Responds
to words it has learned under
program control.

Cat No. 1692 $19.95

APPLE SOFTWARE

buy any 3, take 10% off

Cat No.

Description

Price

1317

Sargon Chess,

19.95

1695

Tic-Tac-Talker/

16K

Spectrum Analy-

11%

Bridge Chal-

14.95

sis, 24K

lenger, 16K

16%

Bomber, 16K

1592

Bowling/Trilogy,

7.95

1697

Rocket Pilot/

20K

Saucer Invasion,

1587

Golf, Applesoft

7.95

16K

II + 20K

1699

Star Wars/Space

1701

Daily Biorhythm,

7.95

Maze, 16K

16K

1693

Music Kaleido-

1656

Galactic Block-

9.95

scope, 16K

ade Runner, 16K

1719

Personal Finance

1658

Sci-Fi Game

7.95

Package, 16K

Sampler, 16K

1697

Apple 21 (Black-

1662

Othello III, 16K

7.95

jack), 16K

9.95

12.95

TRS

COMPUTALKER

SPEECH

SYNTHESIZER

The finest low cost, high quality
electronic speech synthesizer: Pro-
grammable to any language or
dialect.

Cat No. 1917

For the TRS80 485 00 I

16K TRS-80
MEMORY cos
ADD-ON

Installs in minutes! Everything
you need to upgrade to 16K,
32K, or 48K. Guaranteed to
work in your machine.

Cat No. 1156

For TRS-80 keyboard unit
Cat No. 11 56- A

Exp. Inter. Prior to 4/1/79
Cat No. 1156-B

Exp. Inter. After 4/1/79

TRS-232
SERIAL INTERFACE

Software driver RS-232 output.
Interface Diablo, Teletype, Tl
Silent, etc., without expansion
interface! OID

[ Cat No. 1199

MATCHLESS SYSTEMS

TRS-80

| MINIDISK DRIVEl
$395
2 for $775

Faster accessing, increased data
storage. Complete and ready to
plug-in and go! Full 120 day
MONEY BACK guarantee!

Cat No. 1375

TRS-80 DIN PLUGS |

2 for $1.50

Male, plugs into keybd unit & I
accessories.

Cat No. 1229

TRS-80 SOFTWARE

buy any 3, take 10% off

Cat No.

Description

Price

1341

Fortran (Micro-

$275.00

1481

Backgammon,

10.95

soft) L2, 48K +

L2, 16K

disk

1048

Machine Lan-

23.95

1725

CP/M, L2, 16K

149.95

guage Monitor,

+ disk

L1/L2

1039

Renumber 4K -

14.95

1042

Tarot, L1/L2, 4K

5.95

48K

1706

Music Master, L2

14.95

1680

Renumber, 16 •

19.95

+ 16K (plays

48K + disk

music)

1549

Newdos +

99.95

1195

Bridge Chal-

14.95

1685

Electric Paint-

14.95

lenger, L2 + 16K

brush

1186

Air Raid (real

14.95

1681

Syscop (copies

9.95

time target game)

SYSTEM tapes

L1/L2 + 4K

1332

Level III Basic,

49.00

1577

Personal Finance

9.95

L2 + 16K

Package, LI +

1338

Electric Pencil,

95.00

4K, L2 + 16K

cassette

1182

Microchess,

19.95

1199

TRS-232 Serial

49.00

L1/L2 + 4K

Interface

1046

The Game of

14.95

1041

Star Trek III, L2,
16K

14.95

Life, L1/L2 + 4K

S-lOO

TARBELL

I Cat No. Description Price

1756 Cassette Inter- $120.00
face kit

1757 as above, a&t

1901 Floppy Disk
Interface kit

1774 as above, bare-
board

1758 Disk Basic on
CP/M disk

1902 Cassette BASIC

i 1773 32K Static Ram 620.00

kit

175.00

190.00

39.00

70.00

48.00

CENTRONICS
PARALLEL &
SERIAL

MICROPRINTERS I

A non impact desktop microprinter |
perfectly suited for todays per-
sonal computers, microprocessor
development systems, diagnostic
systems, CRT Ftard copy and more!

40 column.

Cat No. 1843* Parallel $445
Cat No. 1844* Serial $515

S-lOO

EDGE

CONNECTORS

Buy any 3, take

10% off

Cat No. Description
1376 Imsai type,
soldertail

1428 Imsai type,
wrap

1388 Altair type,
soldertail

Price

$4.00

SSM

COMPUTER BOARDS

buy any 3, take 10% off

Cat No.
1411
1413
1417

1419
1440
1408
1410
1400 A
1402
1405
1407
1425

1420
1424

Description
104 kit
104 bb
VB1B kit
VB1B bb
PB1 kit
SB1 kit
SB1 bb

MB6B kit 450ns
MB6B bb
MB7 kit
MB7 bb
MB3 kit

MB4 kit, 2 MHz
MB4 bb

Price

$139.00

26.00

129.00

26.00

129.00

150.00

35.00

139.00

26.00

325.00
26.00

54.00

80.00
26.00

1433

1435

1436
1429
1431

1427

1428

1403

1442

1414

1416

MB8A kit
MB8A bb
MB9 kit
OBI kit
OBI bb
XB1

Connector for
XB1

CB1 kit

Tl (Terminator)
kit

102 kit
102 bb

78.00

26.00

64.00

45.00

26.00
10.00

4.00

119.00

29.00

48.00

26.00

PET

SOUNDWARE

Add music and sound effects to I
YOUR computer programs. Com-
plete system with speaker/amplifier
unit volume control, earphone
jack and plug in connectors. Com-
plete Demo and Sound Composer I
programs included.

Cat No. 1899 PET 29.95

COMMODORE
PET/CBM

All Pet computers and peripherals,
both old and new are now avail-

Cat No.

1823 8k bytes, large key-
board; numeric
keypad and graph-
ics on keys.

1824 1 6k bytes, large
keyboard, numeric
keypad and graph-
ics on keys.

1825 32 bytes, large key- $1165
board, no graphics
on keys.

$750

$965

able. Listed below is a sampling of
extensive inventory.

1826 80 column dot ma- $965
trix tractor feed
printer

1827 Dual drive mini $1088

floppy system, 343k

net user storage
capacity

PET
ISOFTWAREI

buy any 3, take 10% off

Cat No. Description Price

1682 Basic Assembler $29.95

for the PET
1713 PET Graphics

1661 Othello, 8K

1700 Daily Biorhythm, 7.95

1718 Personal Finance 9.95

Package

1665 Bridge Chal-

lenger, 8K

1664 Microchess, 8K

1568 Qubic-4/Go-

Moku, 8K
k 1 564 Trek-X, 8K

14.95

7.95

14.95

19.95

7.95

7.95 J

Pay by check, COD, Visa,
or Mastercharge. Order
by phone or mail. Mini-
mum order $10. Please
include phone number and
I magazine/issue you are
ordering from. USA: Add
$2 for shipping/handling
ground; $3 for air.
FOREIGN: Add $3 for

surface, $6 for air. COD's
SI add'tl. Guaranteed sat-
isfaction for 120 days or
your money back! Not re-
sponsible for typographical
errors. We reserve the |
right to limit quantities.

Dept, kio NORTH RIDGE, CA. 91324

v* Reader Service— see page 227

Microcomputing, October 1979 1 95

Save $ on TRS-80 Products

.\\ TREMENDOUS
^1** SAVINGS ON
^ TRS-80 SYSTEMS

Complete system includes:

TRS-80 Level II, w/our 48K RAM, Dual MPI
Disk Drives, and the APPARAT DOS+ soft-
ware ($2500 value), only $2049. Line printer
and desk options available.

SUPERDISK

TF-7D Micropolis Largest capacity
mini floppy, up to 1 95 Kbytes
on 77 tracks with 77TK DOS+ $699

Send for FREE
Catalog

A Complete Family
Of Disk Drives
To Choose
From . . .

In Stock

TF-1 Pertec FD200, 5 V 4 ”, 40 track use both sides $379

TF-3 Shugart SA400, 5V4”, 35 tracks same as tandy $389

TF-5 MPI 5 V 4 ” 40 track door lock and auto diskette $379

ejection

TDH-1 Pertec Dual Head mini-floppy 35 track same $499

capacity as 2 drives

All disk drive systems come complete with power supply and
chassis

• Two drive cable= $25 • Four drive cable= $35

PRINTERS PRINTERS PRINTERS PRINTERS

LP779 Centronics 779
w/tractors

LP700 Centronics 700
LP701 Centronics 701
NEC Spinwriter

$1099

$1175

$1759

$2499

CENTRONICS 703

LP702 Centronics 702 $1899

LP703 Centronics $2540

LP1 Centronics PI $ 399

Centronics cables $ 39

Add-on Disk Drives

DOES NOT INCLUDE POWER SUPPLY OR CHASSIS

• Pertec FD200 or MPI B-52

• Shugart SA400 (unused)

• Pertec Dual Head

$272.00

$282.00

$399.00

NEW PRODUCTS

• Small System RS232 Interface $ 49.00

• Expansion Interface w/32K $499.00

• AC Line Interference Eliminator $ 18.95

• AC Isolator (6 connectors) $ 45.95

• Telephone Interface $179.95

• Verbatum 5” soft sector Diskettes $ 3.39

IMPROVE TRS-80
PERFORMANCE WITH
NEWDOS+

Over 200 modifications,
corrections and enhance-
ments to TRS DOS.

Includes utilities. Available in
two versions:

35 Track version $99
40 T rack version $110

fil

All prices cash discounted.
Freight FOB/Factory

Memory

16KM 16K RAM Kit
Computer $74
Expansion Interface $78

/MlCROCO/HPUrER

TECHNOLOGY
i INCORPORATED

2080 South Grand Ave.
Santa Ana, CA 92705
(714) 979-9923

Software

Accounts Receivable $39
Inventory Control $39
Job Entry/Status $75
General Ledger $79

Game Diskette $19

AJA Word Processor $75

6000 E. Evans Ave., Bldg. 2
Denver, CO 80222
(303) 758-7275

pparat, Inc.

1 96 Microcomputing, October 1979

iS M82

ATTENTION ELF OWNERS
ANNOUNCING QUEST SUPER BASIC

At last a Full Size Basic for 1802 systems. A
complete function Basic including two dimen-
sional arrays, string variables, floating point,
arithmetic and 32 bit signed integer arithmetic
(10 digit accuracy) with I/O routines. Easily adap-
table on most 1802 systems. Requires 12K RAM
minimum for Basic and user programs. Cassette
version in stock now for immediate delivery.
ROM versions coming soon with exchange
privilege allowing credit for cassette version.
Super Basic on Cassette $40.00

Tiny Basic Source now available $19.00
S-100Slot Expansion. Add 3 more S-100 slots to
your Super Expansion Board or use as a 4 slot
S-100 Mother Board. Board without connectors

$9.95.

Coming Soon: High resolution alpha/numerics
with color graphics expandable up to 256 x 192
resolution for less than $100. Economical ver-
sions for other popular 1802 systems also.

16K Dynamic RAM board expandable to 32K for
less than $150.

RCA Cosmac Super Elf Computer $106.95

Compare features before you decide to buy any
other computer. There is no other computer on
the market today that has all the desirable bene-
fits of the Super Elf for so little money. The Super
Elf is a small single board computer that does
many big things. It is an excellent computer for
training and for learning programming with its
machine language and yet it is easily expanded
with additional memory, Full Basic, ASCII
Keyboards, video character generation, etc.

Before you buy another small computer, see if it
includes the following features: ROM monitor:

State and Mode displays; Single step: Optional
address displays; Power Supply; Audio Amplifier
and Speaker; Fully socketed for all IC's; Real cost
of in warranty repairs; Full documentation.

The Super Elf includes a ROM monitor for pro-
gram loading, editing and execution with SINGLE
STEP for program debugging which is not in-
cluded in others at the same price. With SINGLE
STEP you can see the microprocessor chip opera-
ting with the unique Quest address and data bus
displays before, during and after executing in-
structions. Also, CPU mode and instruction cycle
are decoded and displayed on 8 LED indicators.

An RCA 1861 video graphics chip allows you to
connect to your own TV with an inex pen sive video
modulator to do graphics and games. There is a
speaker system included for writing your own
music or using many music programs already
written. The speaker amplifier may also be used
to drive relays for control purposes.

A 24 key HEX keyboard includes 16 HEX keys
plus load, reset, run, wait, input, memory pro-
tect, monitor select and single step Large, on
board displays provide output and optional high
and low address. There is a 44 pin standard
connector slot for PC cards and a 50 pin connec-
tor slot for the Quest Super Expansion Board.
Power supply and sockets for all IC’s are in-
cluded in the price plus a detailed 127 pg. instruc-
tion manual which now includes over 40 pgs. of
software info, including a series of lessons to
help get you started and a music program and
graphics target game.

Many schools and universities are using the
Super Elf as a course of study. OEM’s use it for
training and research and development.
Remember, other computers only offer Super Elf
features at additional cost or not at all. Compare
before you buy. Super Elf Kit $106.95, High
address option $8.95, Low address option
$9.95. Custom Cabinet with drilled and labelled
plexiglass front panel $24.95. Expansion Cabinet
with room for 4 S-100 boards $41.00. NiCad
Battery Memory Saver Kit $6.95. All kits and
options also come completely assembled and
tested.

Questdata. a 12 page monthly software publica-
tion for 1802 computer users is available by sub-
scription for $12.00 per year.

Tiny Basic Cassette $10.00, on ROM $38.00,
original Elf kit board $14.95.

Super Expansion Board with Cassette Interface S89.95

This is truly an astounding value! This board has
been designed to allow you to decide how you
want it optioned. The Super Expansion Board
comes with 4K of low power RAM fully address-
able anywhere in 64K with built-in memory pro-
tect and a cassette interface. Provisions have
been made for all other options on the same
board and it fits neatly into the hardwood cabinet
alongside the Super Elf. The board includes slots
for up to 6K of EPROM (2708, 2758, 2716 or Tl
2716) and is fully socketed. EPROM can be used
forthe monitor and Tiny Basic or other purposes.
A IK Super ROM Monitor $19.95 is available as
an on board option in 2708 EPROM which has
been preprogrammed with a program loader/
editor and error checking multi file cassette
read/write software, (relocatible cassette file)
another exclusive from Quest. It includes register
save and readout, block move capability and
video graphics driver with blinking cursor. Break
points can be used with the register save feature
to isolate program bugs quickly, then follow with
single step. The Super Monitor is written with
subroutines allowing users to take advantage of

monitor functions simply by calling them up.
Improvements and revisions are easily done with
the monitor. If you have the Super Expansion
Board and Super Monitor the monitor is up and
running at the push of a button.

Other on board options include Parallel Input
and Output Ports with full handshake. They
allow easy connection of an ASCII keyboard to the
input port. RS 232 and 20 ma Current Loop for
teletype or other device are on board and if you
need more memory there are two S-100 slots for
static RAM or video boards. A Godbout 8K RAM
board is available for $135.00. Also a IK Super
Monitor version 2 with video driver for full capa-
bility display with Tiny Basic and a video interface
board. Parallel I/O Ports $9.85, RS 232 $4.50,
TTY 20 ma l/F $1.95, S-100 $4.50. A 50 pin
connector set with ribbon cable is available at
$12.50 for easy connection between the Super
Elf and the Super Expansion Board.

The Power Supply Kit for the Super Expansion
Board is a 5 amp supply with multiple positive and
negative voltages $29.95. Add $4.00 for shipping.
Prepunched frame $7.50. Case $10.00. Add $1.50
for shipping.

Multi-volt Computer Power Supply

8v 5 amp, ±18v .5 amp, 5v 1.5 amp, -5v I
.5 amp, 12v .5 amp, -12 option. ±5v, ±12v
are regulated. Kit $29.95. Kit with punched frame |
S37.45. Woodgrain case $10.00.

60 Hz Crystal Time Base Kit $4.40

Converts digital clocks from AC line frequency
to crystal time base. Outstanding accuracy. Kit
includes: PC board, 1C, crystal, resistors, ca-
pacitors and trimmer.

7490N
7492N
7493N
7495N
74100N
74107N
74121 N
741 23N
74125M
74145W
74150N
74151N
741 54N
74157M
741 61 N
741 62N
741 63N
74174N
74175N
74190N
741 92N
74193N
74221 N
74298N
74365 N
74366N
74367M

74LS00 TTL

74LS00N 25
74LS02N .25
74LS04N 25
741S35N 25
741S08N 25
74LS10N 25
74LS13N 40
74LS14N 90
74LS20N 25
74LS22N 25
74LS28N 41
74LS30N 25
74LS33N 39
74LS38N .30
74LS74N 70
74LS75N 47
74LS90N 51
74LS93N 51
74LS95N 189
74LS107N .35
74LS112N .35
74LS113N .35
74LS132N .72
74LS136N 35
74LS151N .67
74LS155H 67
74LS157N .67
741S162N .91
74LS163N 91
74LS174N .95
741S190N 1.06
74LS221N 1 95
741S258N 67
74LS367N 1 35

CA3045
CA3046
CA3081 1

CA3062 1

CA3089 2

LM301
AN/AH
LM305H
LM307N
LM308N
LM3Q9H 1
LM309K 1
LM311H/N

IM317T/K 2.92
LM318 1.35

IM320K-5 1.20
IM323K 5 6 95
LM320K-12 1 35
LM320K-15 1 35
IM320T-5 1 60

LM320T-8 1 60
LM320T-12 1 50
LM320T-15 1.60
LM324N 115
LM339N 1.55
LM340K-5 1 35
LM340K 8 1 35
LM340K-12 1 35
LM340K-15 1.35
LM340K-24 1.35
LM340T-5 1.25
LM340T-8 125
LM340T-12 1.25
IM340T-15 1 25
LM340T18 1 25
LM340T-24 1 25
LM343H 4 50
LM3S0 7.50
LM370 1.15

LM377 3.00

LM379 5 00

LM380N 1 00
LM381 160

LM382 1.60

LM703H 40
LM709H 28
LM7?3H'N 50
LM733N 67
LM741CH .35
LM741N 25
LM747H/N 62
LM748N 35
LM1303N 82

LM1304 1 10

LM1305 1 27

IM1307
LM1310
LM 1 450
LM1800
L VII 81 2
L Ml 889
LM2111
LM2902
LM3900N

LMMOS
M30OM
MCI 458V
NE540L
NE550N
NE555V
NE556A
NE565A
NE566V
NE567V
NE570B
NE571B

78105 .60

78L08 60

78M05 85

75108 1.75

7549 1CN 50

75492CN 55

75494CN 89

AtoD

CONVERTER

8038B 4.50

P.O. Box 4430S Santa Clara, CA 95054
.For will call only: ( 408 ) 988-1640

^^^^^^For will call only: I 408 ) 988-1640
2322 Walsh Ave. ^

uuo/L

ELECTRONICS

2.75

3 :o

2.89

5.00

8730CJ

8701CN

8750CJ

LD130

94O0CJV/F 7 40
ICL7103 950

ICL7107 14.25

Fair

CD4000

CD4001

004002

CD40C6

CD4007

CD4008

CD4000

CD4010

CD4011

CD4012

CD4013

C04014

CD4021
CO 4022
CD4023
CD4024
CD4025
CD4026
CD4027
CD4028
CO 4029
C04030
CD4035
C04040
CD4042
CD4043
C04044
C0404I
C0404I
304050
CD4051
C 04060
CD4066
CO4068
CD4069
004070
CO4071
CD4072
CO 40 73
C0407S
CO4076
CD4078
CD4C8I
CD4082
CD4116
CD4490
C04507
C04508
CO 4510
C04511
CD45I5
CD4516
CD451B
CO 45 20
C04527
C04528
CD4553
CD4566
CD4583
CD4585
C040192 3.00

74COO .28

74C04 .33

74C10 .28

74C14 2.10

74C20 28

74C30 28

74C48 195

74C74 .75

74C76 140

74C90 115

74C93 140

74C154 300

74C160 1 44

74C175 1.35

74C192 165

74C221 2 00

74C905 3.00

74C906 .75

74C914 195

74C922 5 50

74C923 5 50

74C925 6 95

74C926 6 95

74C927 6 95

8T09

8T10

8T13

BT20

8T23

8T24

8T25

BT26

8T28

8T97

8T98

2101-1
2102-1
2102AI-4
21102-1
21F02
2104A-4
2107B-4
2111-1
2112-2
2114L-3
4116
251 36
MM5262
MM5280
MM5320
MM633B
P04110-3
P0411D-4
P5101L
4200A
62S25
91102A
HD0165-5 6 95

MM57100 4.50

GIAY3850O-1 9 95

MCM6571A 9 95

9368 3 50

4100 1000

416 16.00

CLOCKS

MM5314 3 90

MMS315 4 00

MM5369

3.95

7.90

1095

400
500
13.95
995
2 90

N82S136

N82S137

2708

0M8577

8223

2716T1

2716 Intel

2 BO

i to

29 50
48.00

CONNECTORS
44 pin edge 2.75
100 pin edge 4.50
100 pm edge WW 5 25

14 .14 24 .35

WIRE WRAP LEVEL 3

2.10
14.45
7 95
5 80
895

RESISTORS V, wan 5%

10 per type 03 1000 per type 012

25 per type 025 350 piece pack
100 per type .015 5 per type 6 75

KEYBOARDS

56 key ASCII keyboard kit $67.50
Fully assembled 77.50

53 key ASCII keyboard kit 60 00
Fiily assembled 70.00 Enclosure 14.95

LEDS

ReOTOia 15

Green. Yellow T018 20

Jumbo Red .20

Green. Orange. Yellow Jumbo 25
CliplltB LED Mounting Clips 8/SI 25
(specify red. amber, green, yellow, dear)

CONTINENTAL SPECIALTIES in stock
Complete line of breadboard lest Mulp.
MAX-100 8 digit Freq Ctr. $128.95

SPECIAL PRODUCTS

MM566S Stopwatch Timer 5
PC board i

Switches Mom Pushbutton
3 pos side

Encoder HD016S-S (

: 25

MM5B65
CT7001
CT7010
CT7015
MM5375AA/N 3 90
MM5375AG/N 4 90
7205 16 50

7207 7.50

7208 1 5 95

7209 4 95

DS0026CN 3 75
DS0056CN 3.75

MM53104 2 50

280A
8212
8214
8216
8224
8228
8251
8253
8255
8257
8259
1802CP

pas. 13.95

18020P

plas. 17.95

1861 P 11.50

C0P1802CO 19.95

COP18020 25.00

COP1861 12.95

6820 9.95

6850 12.95

6502 12.50

6504 16.50

6522 13 60

UART/FIFO

AY5-1013 5 50

AYS-101 4 7.50

3341 6 95

PROM

1702A 3.95

N82S23 2 95

N82S123 3.50

N82S126 3 75

N82S129 3 75

N82S131 3 75

1000
9 25
19 50
1950

5 MHz
10 MHz
18 MHz
20 MHz
32 MHz
32768 MHz

1 8432 MHz
3 5795 MHz

2 0100 MHz

2 097152 MHz
2.4576 MHz

3 2768 MHz
5 0688 MHz
5 185 MHz
5.7143 MHz
6.5536 MHz
14.31818 MHz
18.432 MHz
22.1184 MHz

KEYBOARD ENCODERS

AY5-2376 $12 50

AY5-3600 17 95

74C922 5 50

74C923 5 50

HD0165-5 6.95

D Connectors RS232

DB25P 295

0B25S 395

Cover 1 50

RS232 Complete Set 6 50
DE9S
DA15P
0A15S

d Kit

Paralromcs 100A Logic

Expander i it.
Model 150 Bus
Grabber Kit
Sinclair 3VY Digit

2.10

TRANSISTORS

2N1893

2N2222A

2N2369

2N2904A

2N2907A

2N3053

2N3638

2N3643

2N3904

2N3906

2N3055

2N4400

2N4401

2N4402

TIP31

TIP33A

Clock Calendar Kit S23.IS
2.S MHz Frequency Counter
Kit $37. JO

30 MHz Frequency Counter
Kit $47.75

TRANSFORMERS

6V 300 ma 3.25

12 Volt 300 ma transformer 1 .25
12.6V CT 600 ma 3.75

12V 250 ma wall plug 2 95
12V CT 250 ma wall plug 3.50
24V CT 400 ma 3.95

DISPLAY LEOS

MAN! CA .270

MAN 3 CC 125

MAN72/74 CA/CA 300

DL704 CC .300

OL 707/D L707R CA 300

DL727/728 CA/CC .500

01747/750 CA/CC .600

01750 CC 600

FND359 CC 357

FND5OO/S07 CC/CA 500

FN0503/510 CC/CA .500

FND800/807 CC/CA .800

3 digit Bubbre

4 digit Bubble
DG8 Fluorescent
DG10 Fluorescent

5 digit 14 pm display
NSN69 9 digit display
7520 Oairex photocells
TIL311 Hex

MA1002A 8.95

MA1012A 895

102P3 transformer 2.25

Rockwell AIM 65 Computer

6502 based single board with full ASCII keyboard
and 20 column thermal printer. 20 char, al-
phanumeric display, ROM monitor, fully expand-
able. $375.00 . 4K version $450.00 . 4K Assem-
bler $85.00, 8K Basic Interpreter $100.00.
Power supply assy, in case $60.00. AIM 65 in
thin briefcase with power supply $485.00.

Not a Cheap Clock Kit $14.95

Includes everything except case. 2- PC boards.
6-. 50" LED Displays. 5314 clock chip, trans-
former, all components and full instructions.
Orange displays also avail. Same kit W/.80"
displays. Red only. $21.95 Case $11.75

Video Modulator Kit $8.95

Convert your TV set into a high quality monitor
without affecting normal usage. Complete kit
with full instructions.

S-100 Computer Boards

8K Static RAM Kit Godbout $135.00

16K Static RAM Kit 265.00

24K Static RAM Kit 423.00

32K Dynamic RAM Kit 310.00

64K Dynamic RAM Kit 470.00

8K/16K Eprom Kit (less PROMS) $89.00

Video Interface Kit $139.00

Motherboard $39. Extender Board $8.99

79 1C Update Master Manual $35.00

Complete 1C data selector, 2500 pg. master refer-
ence guide Over 50,000 cross references. Free
update service through 1979. Domestic postage
$3.50. 1978 1C Master closeout $19.50. No foreign
orders.

Auto Clock Kit $17.95

DC clock with 4-. 50" displays. Uses National
MA-1012 module with alarm option. Includes
light dimmer, crystal timebase PC boards. Fully
regulated, comp, instructs. Add $3.95 for beau-
tiful dark gray case. Best value anywhere.

Stopwatch Kit $26.95

Full six digit battery operated. 2-5 volts.
3.2768 MHz crystal accuracy. Times to 59
min. , 59 sec. . 99 1/100 sec. Times std. , split
and Taylor. 7205 chip, all components minus
case. Full instructions.

NiCad Battery Fixer/Charger Kit

Opens shorted cells that won't hold a charge
and then charges them up, all in one kit w/full
parts and instructions. $7.25

PROM Eraser

Will erase 25 PROMs in 15 minutes. Ultra-
violet, assembled $34.50

Hickok V /2 Digit LCD Multimeter

Batt/AC oper. O.Imv-IOOOv. 5 ranges. 0.5%
accur. Resistance 6 low power ranges 0.1
ohm-20M ohm. DC curr. .01 to lOOma. Hand
held, 'hr LCD displays, auto zero, polarity, over-
range. $69.95.

Digital Temp. Meter Kit $39.95

Indoor and outdoor. Switches back and forth.
Beautiful. 50" LED readouts. Nothing like it
available. Needs no additional parts for com-
plete, full operation. Will measure 100° to
+ 200°F, tenths of a degree, air or liquid.
Beautiful woodgrain case w/bezel $11.75

TERMS: $5.00 min. order U.S. Funds. Calif residents add 6% tax.
BankAmericard and Master Charge accepted.

Shipping charges will be added on charge cards.

FREE: Send for your copy of our NEW 1979
QUEST CATALOG. Include 28c stamp.

iS Reader Service— see page 227

Microcomputing, October 1979 197

AIM 65

BY ROCKWELL INTERNATIONAL

AIM 65 Is fully assembled, tested and warranted. With the
addition of a low cost, readily available power supply, it’s
ready to start working for you.

AIM 65 features on-board thermal printer and
alphanumeric display, and a terminal-style keyboard. It
has an addressing capability up to 65K bytes, and comes
with a user-dedicated IK or 4K RAM. Two installed 4K
ROMS hold a powerful Advanced Interface Monitor
program, and three spare sockets are included to expand
on-board ROM or PROM up to 20K bytes.

An Application Connector provides for attaching a TTY
and one or two audio cassette recorders, and gives exter-
nal access to the user-dedicated general purpose I/O lines.

Also included as standard are a comprehensive AIM 65
User’s Manual, a handy pocket reference card, an R6500
Hardware Manual, an R6500 Programming Manual and an
AIM 65 schematic.

AIM 65 is packaged on two compact modules. The
circuit module is 12 inches wide and 10 inches long, the
keyboard module is 12 inches wide and 4 inches long.

They are connected by a detachable cable.

THERMAL PRINTER

Most desired feature on low-cost microcomputer systems . . .

• Wide 20-column printout

• Versatile 5x7 dot matrix format

• Complete 64-character ASCII alphanumeric format

• Fast 120 lines per minute

• Quite thermal operation

• Proven reliability

FULL-SIZE ALPHANUMERIC KEYBOARD

Provides compatibility with system terminals . . .

• Standard 54 key, terminal-style layout

• 26 alphabetic characters

• 10 numeric characters

• 22 special characters

• 9 control functions

• 3 user-defined functions

TRUE ALPHANUMERIC DISPLAY

Provides legible and lengthy display . . .

• 20 characters wide

• 16-segment characters

• High contrast monolithic characters

• Complete 64-character ASCII alphanumeric format

PROVEN R6500 MICROCOMPUTER SYSTEM DEVICES

Reliable, high performance NMOS technology . . .

• R6502 Central Processing Unit (CPU), operating at 1
MHz. Has 65K address capability, 13 addressing modes
and true index capability. Simple but powerful 56
instructions.

• Read/Write Memory, using R2114 Static RAM devices.
Available in IK byte and 4K byte versions.

• 8K Monitor Program Memory, using R2332 Static ROM
devices. Has sockets to accept additional 2332 ROM or
2532 PROM devices, to expand on-board Program
memory up to 20K bytes.,

• R6532 RAM-Input/Output-Timer (RIOT) combination
device. Multipurpose circuit for AIM 65 Monitor functions.

• Two R6522 Versatile Interface Adapter (VIA) devices,
which support AIM 65 and user functions. Each VIA has
two parallel and one serial 8-bit, bidirectional I/O ports,
two 2-bit peripheral handshake control lines and two
fully-programmable 16-bit interval timer/event counters.

BUILT-IN EXPANSION CAPABILITY

• 44-Pin Application Connector for peripheral add-ons

• 44-Pin Expansion Connector has full system bus

• Both connectors are KIM-1 compatible

TTY AND AUDIO CASSETTE INTERFACES

Standard interface to low-cost peripherals . . .

• 20 ma. current loop TTY interface

• Interface for two audio cassette recorders

• Two audio cassette formats: ASCII KIM-1 compatible
and binary, blocked file assembler compatible

ROM RESIDENT ADVANCED INTERACTIVE MONITOR

Advanced features found only on larger systems . . .

• Monitor-generated prompts

• Single keystroke commands

• Address independent data entry

• Debug aids

• Error messages

• Option and user interface linkage

ADVANCED INTERACTIVE MONITOR COMMANDS

• Major Function Entry

• Instruction Entry and Disassembly

• Display/Alter Registers and Memory

• Manipulate Breakpoints

• Control Instruction/Trace

• Control Peripheral Devices

• Call User-Defined Functions

• Comprehensive Text Editor

LOW COST PLUG-IN ROM OPTIONS

• 4K Assembler— symbolic, two-pass

• 8K BASIC Interpreter

POWER SUPPLY SPECIFICATIONS

• + 5 VDC ± 5% regulated @ 2.0 amps (max)

• + 24 VDC ±15% unregulated @ 2.5 amps (peak)

0.5 amps average

PRICE: $375.00 (IK RAM)

Plus $4.00 UPS (shipped in U.S. must give street address),
$10 parcel post to APO’s, FPO’s, Alaska, Hawaii, Canada,
$25 air mail to all other countries

We manufacture a complete line of high quality expansion
boards. Use reader service card to be added to our mailing
list, or U.S. residents send $1.00 (International send $3.00
U.S.) for airmail delivery of our complete catalog.

ENTERPRISES

INCORPORATED ^R20

2967 W. Fairmount Avenue
Phoenix AZ 8501 7
(602)265-7564

SYM-1, 6502-BASED MICROCOMPUTER

• FULLY-ASSEMBLED AND COMPLETELY INTEGRATED SYSTEM that's
ready-to-use

• ALL LSI ICS ARE IN SOCKETS

• 28 DOUBLE-FUNCTION KEYPAD INCLUDING UP TO 24 "SPECIAL"
FUNCTIONS

• EASY-TO-VIEW 6-DIGIT HEX LED DISPLAY

• KIM-1* HARDWARE COMPATIBILITY

The powerful 6502 8-Bit MICROPROCESSOR whose advanced
architectural features have made it one of the largest selling "micros"
on the market today.

• THREE ON-BOARD PROGRAMMABLE INTERVAL TIMERS available to
the user, expandable to five on-board.

• 4K BYTE # ROM RESIDENT MONITOR and Operating Programs.

• Single 5 Volt power supply is all that is required.

• IK BYTES OF 2114 STATIC RAM onboard with sockets provided for
immediate expansion to 4K bytes onboard, with total memory expan-
sion to 65, 536 bytes.

• USER PROM/ROM: The system is equipped with 3 PROM/ROM ex-
pansion sockets for 2316/2332 ROMs or 2716 EPROMs

• ENHANCED SOFTWARE with simplified user interface

• STANDARD INTERFACES INCLUDE:

— Audio Cassette Recorder Interface with Remote Control (Two
modes: 135 Baud KIM-1* compatible, Hi-Speed 1500 Baud)

— Full duplex 20mA Teletype Interface
— System Expansion Bus Interface
— TV Controller Board Interface
— CRT Compatible Interface (RS-232)

• APPLICATION PORT: 15 Bi-directional TTL Lines for user applications
with expansion capability for added lines

• EXPANSION PORT FOR ADD-ON MODULES (51 I/O Lines included in
the basic system)

• SEPARATE POWER SUPPLY connector for easy disconnect of the d-c
power

• AUDIBLE RESPONSE KEYPAD

Synertek has enhanced KIM-1 * software as well as the hardware. The
software has simplified the user interface. The basic SYM-1 system is
programmed in machine language. Monitor status is easily accessible,
and the monitor gives the keypad user the same full functional capabili-
ty of the TTY user. The SYM-1 has everything the KIM-1* has to offer,
plus so much more that we cannot begin to tell you here. So, if you want
to know more, the SYM-1 User Manual is available, separately.

SYM-1 Complete w/manuals $249.00

SYM-1 User Manual Only 7.00

SYM-1 Expansion 75.00

Expansion includes 3K of 21 14 RAM chips and 1-6522 I/O chip.
SYM-1 Manuals: The well organized documentation package is com-
plete and easy-to-understand.

SYM-1 CAN GROW AS YOU GROW. It’s the system to BUILD-ON.
Expansion features that are available:

BAS-1 8K Basic ROM (Microsoft Basic) 129.00

Kim-2 (Complete terminal less monitor) 349.00

QUALITY EXPANSION BOARDS DESIGNED SPECIFICALLY FOR KIM-1, SYM-1 & AIM 65

These boards are set up for use with a regulated power supply such as the one below, but, provisions have been made so that you can add
onboard regulators for use with an unregulated power supply. But, because of unreliability, we do not recommend the use of onboard
regulators. All I.C/s are socketed for ease of maintenance. All boards carry full 90-day warranty.

All products that we manufacture are designed to meet or exceed industrial standards. All components are first qualtiy and meet full
manufacturer's specifications. All this and an extended burn-in is done to reduce the normal percentage of field failures by up to 75%. To you,
this means the chance of inconvenience and lost time due to a failure is very rare; but, if it should happen, we guarantee a turn-around time of
less than forty-eight hours for repair.

Our money back guarantee: If, for any reason you wish to return any board that you have purchased directly from us within ten (10) days after
receipt, complete, in original condition, and in original shipping carton; we will give you a complete credit or refund less a $10.00 restocking
charge per board.

VAK-1 8-SLOT MOTHERBOARD

This motherboard uses the KIM-4* bus structure. It provides eight (8)
expansion board sockets with rigid card cage. Separate jacks for audio
cassette, TTY and power supply are provided. Fully buffered bus.

VAK-1 Motherboard $129.00

VAK-2/4 16K STATIC RAM BOARD

This board using 2114 RAMs is configured in two (2) separately
addressable 8K blocks with individual write-protect switches.

VAK-2 16K RAM Board with only $239.00

8K of RAM ( Vi populated)

VAK-3 Complete set of chips to $175.00

expand above board to 16K
VAK-4 Fully populated 16K RAM $379.00

VAK-5 2708 EPROM PROGRAMMER

This board requires a +5 VDC and +12 VDC, but has a DC to DC

multiplyer so there is no need for an additional power supply. All
software is resident in on-board ROM, and has a zero-insertion socket.

VAK-5 2708 EPROM Programmer $269.00

VAK-6 EPROM BOARD

This board will hold 8K of 2708 or 2758, or 16K of 2716 or 2516
EPROMs. EPROMs not included.

VAK-6 EPROM Board $129.00

VAK-7 COMPLETE FLOPPY-DISK SYSTEM (May ’79)

VAK-8 PROTYPING BOARD

This board allows you to create your own interfaces to plug into the
motherboard. Etched circuitry is provided for regulators, address and
data bus drivers; with a large area for either wire-wrapped or soldered
1C circuitry.

VAK-8 Protyping Board $49.00

POWER SUPPLIES

ALL POWER SUPPLIES are totally enclosed with grounded enclosures for safety, AC power cord, and carry a full 2-year warranty.

FULL SYSTEM POWER SUPPLY

This power supply will handle a microcomputer and up to 65K of our KIM-1 * Custom P.S. provides 5 VDC @1.2 Amps

VAK-4 RAM. ADDITIONAL FEATURES ARE: Over voltage Protection on 5 and + 1 2 VDC @ . 1 Amps

volts, fused, AC on/off switch. Equivalent to units selling for $225.00 or KCP-1 Power Supply $41 50

more. ,

Provides +5 VDC <

VAK-EPS Power Supply

10 Amps & +12 VDC @ 1 Amp

j|RNEI>

SYM-1 Custom P.S. provides 5 VDC @1.4 Amps
$125.00 VCP-1 Power Supply

KIM is a product of MOS Technology

$41.50

ENTERPRISES

NCORPORATED

iX R20

2967 W. Fairmount Avenue
Phoenix AZ 8501 7
(602)265-7564

v* Reader Service— see page 227

Microcomputing, October 1979 1 99

QTY.

DIODES/ZENERS

1N914

100v

10mA

.05 .

1N4005

600v

1 A

.08

1N4007

lOOOv

1 A

.15

1N4148

75v

10mA

.05

1 N4733

5.1 v

1 W Zenner

.25

1N4749

24v

.25 _

1 N753A

6.2v

500 mW Zener

.25 1

1N758A

lOv

“

.25

IN 759 A

12v

.25

1N5243

13v

.25

1N5244B

14v

.25

1N5245B

1 5v

.25

1N5349

12v

.25

QTY.

SOCKETS/BRIDGES

8-pin

pcb

.16 ww

.35

14-pin

pcb

.20 ww

.40

16-pin

pcb

.25 ww

.45

18-pin

pcb

.30 ww

.95

20-pin

pcb

.35 ww

1.05

25 Amp Bridge 200-prv

1.50

QTY> TRANSISTORS, LEDS, etc.

2N2222M

(2N2222 Plastic .10)

.15

2N2222A

.19

2N2907A

PNP

.19

2N3906

PNP (Plastic)

.19

2N3904

NPN (Plastic)

.19

2N 3054

NPN

.55

2N3055

NPN 15A 60v

.60

T1 PI 25

PNP Darlington

1.95

LED Green,

Red, Clear. Yellow

.19

22-pin

pcb .40

1.15

24-pin pcb .45 ww

1.25

28-pin pcb .50 ww

1.35

40-pin pcb

Molex pins .01

.55 ww
To-3 Sockets

1.45

.35

2 Amp Bridge

1 00-prv

.95

D.L.747 7 seg 5/8" High com-* node 1 .95

MAN72 7 seg com-anode (Red) 1.25

MAN 3610 7 seg com-anode (Orange) 1.25

MAN82A 7 seg com-anode (Yellow) 1.25

7 cpn rnm-rathnHB IRoHl 1

MAN74 7seg com-catho de (Red) 1.50

FND359 7 seg com-cathode (Red) 1 .25

QTY.

9301

9000 SERIES

QTY.

.85 I 9 322

9309

.50

9316

1.25

.65

9601

.30

9602

.45

MM 5314

4.00

MM 5316

4.50

MM 5387

3.50

MM 5369

2.95

TR 1 602B

3.95

UPD 414

4.95

MICRO'S, RAMS,
CPU's, E-PROMS

QTY.

8T1 3 2.50

8T23

2.50

8T24

3.00

8T97

1.75

74S188

3.00

1488

1.25

1489

1.25

1702A

6.50

AM 9050 5.00

I CM 7207 6.95

I CM 7208 13.95

MPS 6520 10.00

Z 80 A

19.50

Z 80

14.50

Z80P10 10.50

2102

1.45

2102L

2107B-4

1.75

T55

2114

9.50

2513 Upper or Lower 7.25

2708

12.50

2716 DS.

29.00

2716 (Sv)

69.06'

2758 (5v)

32.95

3242

10.50

4116

13.50

6800

13.95

6850

7.95

8080

9.50

8085

22.50

8212

8214

3.75

4.95

8216

4.50

8224

5.25

8228

6.00

"S25T

8.50

8253

18.50

8255

9.50

TMS4044

10.95

4000

.20

4001

"400T

.30

.25

4004

“4066"

3.95

loor

_L50

.25

4008

.75

MOS

QTY.

4018

.75

4019

.35

4020

.85

4021

.75

4022

.75

4023

.25

4024

.75

4037

1.80

4040

.75

4041

.69

4042

.65

4043

4044

_i§Q.

.65

4046

1.25

4071

.25

4072

~*5gr

-5555-

.60

SIT

“*507“

"75 rr

-*5T5“

”35-

-TTL-

8-1-79

QTV.

QTY.

7400

.20

7492

.45

74H10

.35

74LS51

.75

7401

.20

7493

.35

74H11

.25

74LS74

1.50

7402

.20

7494

.75

74H15

.45

74LS75

1.20

7403

.20

7495

.60

74H20

.25

74LS76

.70

7404

.45

7496

.80

74H21

.25

74LS86

.95

7405

.35

74100

1.15

74H22

.40

74LS90

.85

7406

.35

74107

.35

74H30

.30

74LS93

.85

7407

.55

74121

.45

74H*0”

” 35“

74LS96

2.00

7408

.40

74122

.55

74H50

.30

74LS107

.90

7409

.25

74123

.55

74H51

.30

74LS109

1.50

7410

.20

74125

.45

74H52

.20

74 LSI 23

1.95

7411

.25

74126

.45

74H53

.25

74 LSI 38

2.00

7412

.25

74132

.75

74H55

.25

74 LSI 51

.95

7413

.45

74141

.90

74H72

.35

74LS153

1.15

7414

.95

74145

1.35

74H74

.35

74LS157

1.15

7416

.25

74150

.85

74H101

.95

74 LSI 60

1.15

7417

.40

74151

1.15

74H103

.55

74LS164

2.90

7420

.25

74153

1.15

74H106

1.15

74LS193

2.00

7426

.25

74154

1.15

74 LOO

.30

74LS195

1.15

7427

.25

74156

.70

74L02

.30

74LS244

2.90

7430

.20

74157

.65

74L03

.35

74LS259

1.50

7432

.50

74161

.95

74L04

.40

74LS298

1.50

7437

.20

74163

.85

74L10

.30

74LS367

2.50

7438

.30

.75

74L20

.45

74LS368

1.25

7440

.20

74165

1.10

74L30

.55

74LS373

2.50

7441

1.15

74166

2.25

74L47

1.95

74S00

.60

7442

.55

74175

.90

74L51

.65

74S02

.45

7443

.45

74176

.95

74L55

.85

74S03

.35

7444

.45

74177

1.10

74L72

.65

74S04

.65

7445

.75

7*180”

.95

74L73

.70

74S05

.45

7446

.70

74181

2.25

74L74

.75

74S08

.65

7447

.70

74182

.75

74L75

Tori

74S10

.45

7448

.50

74190

1.25

74L85

2.00

74S11

.45

7450

.25

74191

1.25

74L93

.75

74S20

.35

7451

.25

74192

.75

74L123

1.95

74S22

.55

7453

.20

74193

.85

74LS00

.60

74S40

.30

7454

.25

74194

.95

74LS01

.40

74S50

.30

7460

.40

74195

.95

74LS02

.55

74S51

.35

7470

.45

74196

.95

74LS03

.45

74S64

.15

7472

.40

74197

.95

74LS04

.65

74S74

1.50

7473

.25

74198

1.45

74LS05

.45

74S112

.60

7474

.50

74221

2.25

74LS08

.65

74S114

.85

7475

.35

74298

1.50

74LS09

.45

74S133

.85

7476

.40

74367

1.35

74 LSI 0

.45

74S140

.75

7480

.75

75451

.65

74LS11

.45

74S151

.95

7481

.85

75452

.65

74LS20

.45

74S153

•95

7482

.95

75491

.65

74LS21

.45

74S157

.98

7483

.95

75492

.65

74LS22

.45

74S158

.80

7485

.75

74H00

.20

74LS32

.60

74S194

2.25

7486

.55

74H01

.30

74LS37

.45

74S196

2.00

7489

1.05

74H04

.30

74LS38

.65

74S257 18123)2.95

7490

.55

74H05

.25

74LS40

.70

8131

2.75

7491

.70

74H08

.35

74LS42

1.25

.95

“4515“

1.25

2.95

QTY.

MCT2

i 2 l, linears, regulators, etc.

QTY.

1.651 LM373

QTY.

.95 LM320K24

3.95

4009

.35

4025

.25

4047

2.50

SQ38

JLa &

LM320T5(7905) 1.65

LM37 7

4010

_^5

4026

JL95

4048

_LZ£

4519

J3&.

-LM2 01

uJS.

UM320J12

1.1

78L05

4011

.35

4027

.35

4049

.65

4522

1.10

- LM301

.45

LM320T1 5

78 U2

-J5.

4012

.25

4028

.75

4050

4526

.95

LM308

LM323K

5.95

78L15

.75

4013

.40

4029

1.15

4052

.75

4528

1.10

LM309H

.85

LM324

1.25

78M05

.75

-*m4“

.75

4030

.30

4053

.95

4 529

_i95_

LM309 (340K-5) 1.50

LM339

.75

LM380 (8-1 4 Pin) 1.19

4015

.75

4033

1.50

4066

.75

MCI 4409 14.50

LM310

.85

7805 (340T5) 1.15

LM709 (8-14 Pin) .45

4016

735

4034

2.45

4069/7 4C04 .45

MCI 441 9 4.85

LM31 1 (8-1 4 Pin) .75

LM340T1 2

.95

LM711

.45

4017

.75

4035

J15.

4070

1.00

74C151 2.50

LM318

1.50

LM340T1 5

LM723

.40

INTEGRATED CIRCUITS UNLIMITED

is 19

7889 Clairemont Mesa Blvd., San Diego, California 92111
Out of State 1 -800-854-221 1 TWX 91 0-335-1 577 Telex: 697-827

(714) 278-4394 California Residents 1-800-542-6239

LM320H6

.79

LM340T1 8

LM320H1 5

.79

.95

LM725

3.50

LM340T24

LM320H24

LM320K5

.79

.95

LM739

1.50

1.65

LM340K1 2 1.25

LM340K1 5

. LM320K12

1.25

LM741 (8-14) .45

LM747

1.10

LM320K1 5

1.65

LM340K18 L25

LM1307

LM340K24

1.25

NAME-

STREET ADDRESS.
CITY

. STATE.

ZIP.

PHONE.

AE Visa

-CHARGE CARD # BA MC _

LM1458

_LZ5_

.65

LM3900 1.50

NE555

.45

NE556

.85

NE565

1.15

NE566

1.25

NE567

.95

TA7205

4.95

76477

2.95

95H90

9.95

EXP. DATE

C.O.D. .

WILL CALL.

POST_

NET 10th OF THE MONTH.

. PO #_

ALL ORDERS SHIPPED PREPAID - NO MINIMUM - COD ORDERS ACCEPTED - ALL ORDERS SHIPPED SAME DAY
OPEN ACCOUNTS INVITED - California Residents add 6% Sales Tax. PRICES SUBJECT TO CHANGE WITHOUT NOTICE.
24 Hour Phone Service — We accept American Express / Visa / BankAmericard / Master Charge

SPECIAL DISCOUNTS

Total Order

Deduct

$35-$99

10%

$100 $300

15%

$301 $1000

20%

200 Microcomputing, October 1979

We Specialize in High Technology

at Low

Econoram* boards are generally available in 3 forms: unkit (sockets and bypass
caps are pre-soldered in place for simple, one-evening assembly), assembled
and tested, or qualified under our high-reliability Certified System Com-
ponent (CSC) program (200 hour burn-in, immediate replacement in event of
failure within 1 year of invoice date). 1 year limited warranty on all products. Refer
to chart below for pricing.

Name

Storage

Buss

Configurations

Notes

Unkit

Assm

CSC

Econoram

IIA

8KX

S-100

2-4 K blocks

$149

$179

$239

Econroam

16K X

S-100

1-16K

$269

$329

$429

Econoram

viiA-ie

16K X

S-100

2-4 K, 1-8K

$279

$339

$439

Econoram

VIIA-24

24K X

S-100

2-4 K, 2-8 K

$398

$485

$605

Econoram

IX-1B

16K X

Dig Grp

2-4K, 1-8K

$319

$379

n/a

Econoram

IX-32

32K X

Dig Grp

2-4 K, 1-8K, 1-1 6K

$559

$639

n/a

Econoram

32K X

S-100

2-8 K, 1-1 6K

$529

$649

$789

Econoram

32K X

SBC/BLC

2-8 K, 1-1 6K

n/a

$1050

Econoram

xii-ie

16K X

S-100

see notes

1,2

$329

$419

$519

Econoram

XII-24

24K X

S-100

see notes

1,2

$429

$539

$649

Econoram

XIII

32K X

S-100

see notes

1,3

$559

$699

$849

Econoram

XIV

16K X

S-100

see notes

1,4,5

$289

$349

$449

Econoram

XV-16

16K X

1-16K

1,6

$329

$395

n/a

Econoram

XV-32

32K X

2-1 6K

1, 6

$599

$729

n/a

Notes:

1. Works at 5 MHz with 8085 or at 4 MHz with Z-80.

2. Bank select board — 2 independent banks addressable on

3. Bank select board — 2 independent banks addressable on

4. Bank select board — 1 bank addressable on 4K boundaries.

8K boundaries. 5. 24 address lines for extended addressing.

16K boundaries. 6. Bank select option for implementing memory systems greater than 64K.

Econoram is a trademark of Bill Godbout Electronics.

••••••••••••••••••••••••••••••••••••••••••••••••••••••

Coming soon: This month, we’re announcing the
Econoram XIV with extended addressing, two new Econorams
(XV-16 and XV-32) for the H8 buss, and our Memory Management
Board. In the next few months, we’ll be introducing...

• 4 MHz Z-80 CPU board

• 5 MHz 8085 CPU board

• Triple Parallel + Single Serial board, with 3 full duplex parallel ports and
serial port with full RS-232 handshake

• 12 and 18 slot motherboards — double sided, shielded, and actively
terminated

• And, a rack mount or desk top enclosure, with power supply, to hold all
this neat stuff

Just thought you ought to know.

16K Memory Expansion
Chip Set S87.20 (regular
$109; 20% off while they last)

This Godbout quality product expands memory in Radio Shack-80, Apple,
and Exidy Sorcerer computers. Our chip set features low power, high speed
(250 ns) parts that work with 4 MHz systems. DIP shunts included. Easy-to-
follow instructions for Radio Shack-80 modification make conversion simple. 1
year limited warranty.

“INTERFACER” S-IOO I/O
S189 unkit, $249 assm

Dual serial port with 2 full duplex parallel ports for RS-232 handshake;
EIA232C line drivers and receivers (1488, 1489) along with current loop (20 mA)
and TTL signals on both ports. Onboard crystal-controlled timebase with in-
dependently selectable Baud rate generators for each part (up to 19.2 KBaud).
This board has hardware LSI UARTs that don’t tie up the computer’s CPU,
operates with 2 to 5 MHz systems, includes software programmable UART
parameters/interrupt enables/handshaking lines, offers provision for custom
frequency compensation on both receive and transmit sides to accommodate
varying speed/noise situations or unusual cable lengths... and even all this
isn’t the full story on what this no-excuses board can do for you.

Econoram II Closeout $129
unkit (3/S375), $155 assm

This is a limited quantity item. Our brand new Econoram IIA is out, but even
by today’s standards the original Econoram II is an excellent memory. 2 MHz
operation, low power, configured as two independent 4K blocks, and one of the
best track records in the industry for reliability and cost-effective operation.
Easy one-evening assembly, 1 year limited warranty on all components.

18 Slot Motherbd Closeout

— was $124, now only $109

Includes on-board active termination, with all 18 edge connectors pre-
soldered in place for easy assembly. Limited quantity.

■ ■ilHIHIHIHIHIHIHIMilHIHilMIHilMilHIHIHilHIMIIHIH

Memory Management

$59 kit, $85 assm, $100 CSC

Now you can add bank select and extended addressing to older S-100
machines like the IMSAI, Altair, Sol, Polymorphic, etc. Either use this board
with our new extended addressing boards, or retrofit our high density
Econorams (the ones with phantom or extra qualifier lines) for use with the
Memory Management Board to get more than 64K of memory space for your
computer.

2708 EROM board
unkit $85

4 independently addressable 4K blocks, with selective disable for each
block. Built to CompuPro/Econoram standards (dipswitch addressing, top
quality board, sockets wave-soldered in place), and includes dipswitch selec-
table jump start built right into the board. Includes all support chips and
manual, but does not include EROMs.

ACTIVE TERMINATOR
kit $34.50

Our much imitated design plugs into any S-100 motherboard to reduce ring-
ing, noise, crosstalk, and other buss-related problems. This is a simple, effec-
tive, low cost way to upgrade your machine.

E COMPUPRO'™ AT A STORE NEAR YOU,

Many Godbout computer products are available under the CompuPro name
at leading computer stores world-wide. Want to see for yourself exactly what kind of
quality and effort we put into turning out cost-effective, high performance boards?
Then see our products in person at a computer store near you.

TERMS: Cal res add tax.

Allow 5% for shipping, excess
refunded. VISA®/Mastercharge f -
call our 24 hour order desk at
(415) 562-0636. COD OK with
street address for UPS. Prices
good through cover month of
magazine.

CompuPro"

Bldg. 725, Oakland Airport, CA 94614

from

*xG4

FREE FLYER: We’ll be

glad to tell you more than the
space of this ad permits. Just
send your name and address,
we’ll take care of the rest. If
you’re in a hurry, enclose 41c in
stamps for 1st class delivery.

iS Reader Service — see page 227

Microcomputing, October 1979 201

7400 TTL

8N7400N

SN7401N

SN7402N

SN7403N

SN7404N

SN7405N

SN7406N

SN7407N

SN7408N

SN7409N

SN7410N

SN7411N

SN7412N

SN7413N

SN7414N

SN7416N

SN7417N

SN7420N

SN7421N

SN7422N

SN7423N

SN7425N

SN7426N

SN7427N

SN7429N

SN7430N

C04000
C04001
CD4002
CD4006
CD4007
CD 4009
CD4010
CD4011
CD4012
CO4013
CD4014
CO4015
CO4016
CD4017
CD4018
CD4019
C04020
CD4021
CD4022
CD4023
CD4024
CD4025
CD4026
CD4027

74COO

74C02

74C04

74C08

74C10

74C14

74C20

74C30

74C42

74C48

74C73

JSEL.

78MG

LM106H

LM300H

LM301CN/H

LM302H

LM304H

LM305H

LM307CN/H

LM308CN/H

LM309H

LM309K

LM31CCN

LM311N/H

LM312H

LM317K

LM318CN/H

LM319N

IM320K-5

LM320K-5.2

LM320K-12

LM320K-15

LM320K-18

LM320K-24

LM320T -5

LM320T-5.2

LM320T-8

LM320T-12

LM320T-15

LM320T-18

LM320T-24

LM323K-5

LM324N

LM339N

LM340K-5

LM340K-6

LM340K B

LM340K-12

LM340K-15

74LS00
74LS01
74LS02
74LS03
74LS04
74LS05
741S08
74LS09
74LS10
74LS1 t
74LS13
74LS14
74LS15
74LS20
74LS21
74LS22
74LS26
74LS27
74LS28
74LS30
74LS32
74LS37
74LS40
^4LS42

SN7470N

SN7472N

SN7473N

SN7474N

SN7475N

SN7476N

SN7479N

SN7480N

SN7482N

SN7483N

SN7485N

SN7486N

SN7489N

SN7490N

SN7491N

SN7492N

SN7493N

SN7494N

SN7495N

SN7496N

SN7497N

SN74100N

SN74107N

SN74109N

SN74116N

SN74121N

SN74122N

SN74123N

.35

1.75

SN74160N

SN74161N

SN74162N

SN74163N

SN74164N

SN74165N

SN74166N

SN74167N

SN74170N

SN74172N

SN74173N

SN74174N

SN7417SN

SN74176N

SN74177N

SN74179N

SN74180N

SN74181N

SN74182N

SN74184N

SN74185N

SN74186N

SN74188N

SN74190N

SN74191N

SN74192N

SN7437N

.25

SN74126N

SN74194N

.200 dia.

SN7438N

.25

SN74132N

.75

SN74195N

.69

XC556R red

5/si

.125" dia.

SN7439N

SN74136N

.75

SN74196N

XC556G green

4/SI

XC209R

red

SN7440N

.20

SN74141N

.79

SN74197N

.89

XC556Y yellow

4/SI

XC209G

green

SN7441N

.89

SN74142N

2.95

SN74198N

1.49

XC556C clear

4/SI

XC209Y

yellow

SN7442N

SN74143N

295

SN74199N

1.49

.200" dia.

.185" dia.

SN7443N

.75

SN74144N

2.95

SN74S200

4 95

XC22R red

5/$1

XC526R

SN7444N

.75

SN74145N

.79

SN74251N

1.79

XC22G green

4 Si

XC526G

SN7445N

.75

SN74147N

1.95

SN74279N

.79

XC22Y yellow

4/SI

XC526Y

green

yellow

SN7446N

.69

SN74146N

1.29

SN74283N

2.25

.170" dia.

XC526C

dear

SN7447N

SN74150N

.89

SN74284N

3.95

MV10B red

4/sr

SN7448N

.79

SN74151N

.59

SN74285N

3.95

.085" dia.

.190' dia.

SN7450N

.20

SN74152N

.59

SN74365N

.69

MV50 red

6/SI

XC111R

red

SN7451N

.20

SN74153N

.59

SN74366N

.69

XC111G

green

SN7453N

.20

SN74154N

.99

SN74367N

.69

IINrnA-r\tLI LtU

XC111Y

yellow

SN7454N

.20

SN74155N

.79

SN74368N

1/4 X1/4 X1/ ID

riat

XC111C

clear

SN7459A

.25

SN74156N

.79

SN74390N

1.95

5/$1

SN74393N 195

C/MOS

CD4028

CD4029

CD4030

CD4035

CD4040

C04041

CD4042

CD4043

CD4044

004046

CD4047

CD4048

CO4049

CD4050

CD4051

CD4053

C04056

CD4059

CD4060

CD4066

CD4068

CD4Q69

1.19
1 '0
2.95
9 95
1 49

74COO

74C85

74C90

74C93

74C95

74C107

74C151

740154

74C157

74C160

74C161

1.95
1.25
2.90
3.00
2.15
249
2 49

LM340K-18 1.35

LM340K-24 1.35

LM340T-5
LM340T-6
LM340T-8
LM340T-12
LM340T-15 1.25

LM340T-18 1.25

LM340T-24 1.25

LM358N
LM370N
LM373N
LM377N
LM380N
LM380CN
LM381N
LM382N
NE501N
NE510A
NE529A
ME531H/V
NE536T
NE540L
NE544N
NE550N
ME555V
NE556N
NE560B
NE561B
NE562B
NE565N/H
NE566CN
NE567V/H
NE570N
LM703CN/H
LM709N/H

1.25
1.25
1 25

1.00

1.79

39
99
500
5 N
5.00
1.25
1.75
.99
4.95

74LS00TTL

74LS47 .89
74LS51 29
74LS54 .29
74LS55 .29
74LS73 45
74LS74 .45
74LS75 .59
74LS76 45
74LS78 49
74LS83 89
74LS85 125
74LS86 .45
74LS90 .59
74LS92 75
74LS93 75
74LS95 .99
74LS96 1.15
74LS107 45
74LS109 45
74LS112 45
74LS123 1.25
74LS125 89
74LS132 99
74LS136 49

C04070

C04071

C04072

CD4076

CD4081

C04082

CD4093

CD4098

MCI 4409

MC14410

MCI 441 1

MC14419

MCI 4433

MCI 4506

MC14507

MC14562

MCI 4583

CO4506

CD4510

CD4511

CD4515

CD4518

CD4520

C04566

74C163

74C164

74C173

74C192

74C193

74C195

74C922

74C923

74C925

74C926

80C95

80C97

2.49
2.49
2.60
2 40
249

2.49
595
6.25
8.95
8.95

1.50
1.50

LINEAR

LM710N .79

LM711N .39

LM723N/H .55
LM733N 1.00
LM739N 1.19
LM741CN/H .35
LM741-14N .39

LM747N/H .79
LM748N/H .39
LM1310N 2.95

LM1458CN/H .59
MC1488N 1.39

MC1489N 1.39

LM1496N .95

LM1556V 175

MC1741SCP 3.00
LM2111N 1.95

LM2901N 2.95

LM3053N 1.50

LM3065N 1.49

LM3900N(3401) .49
LM3905N .89

LM3909N 1.25

MC5558V .59

8038B
LM75450N
75451CN
75452CN
75453CN
75454CN
75491CN
75492CN
75493N
75494CN
RC4136
RC4151
RC4194
RC4195

495

2.85

5.95

4.49

74LS138

74LS139

74LS151

74LS155

74LS157

74LS160

74LS161

74LS162

74LS163

74LS164

74LS175

74LS181

74LS190

74LS191

74LS192

74LS193

74LS194

74LS195

74LS253

74LS257

74LS258

74LS260

74LS279

74LS367

74LS368

74LS670

.75

EXCITING NEW KITS

JE600 HEXADECIMAL
ENCODER KIT

FEATURES:

• Full 8 bit latched output for micro-
processor use

• 3 User Define keys with one being bi-
stable operation

■ Debounce circuit provided tor all 19
keys

• LED readout to verify entries

• Easy interfacing with standard 16 pin

Digital

Thermometer Kit

• Only +5VOC required lor operations
FULL 8 BIT LATCHED OUTPUT-19 KEYBOARD
The JE600 Encoder Keyboard provides two separate hexadecimal
digits produced from sequential key entries to allow direct prog-
ramming for 8 bit microprocessor or 8 brt memory circuits Three
(3) additional keys are provided lor user operations with one having
a bistable output available The outputs are latched and monitored
with LED readouts. Also included is a key entry strobe.

JE600 $59.95

Hexadecimal Keypad only $14.95

■ Dugl sensors— switching control for in-
door/outdoor or dual monitoring
■Continuous LED .8" ht. display
•Range: -40°F to 199°F / -40°C to 100°C
•Accuracy: ±1° nominal
•Set for Fahrenheit or Celsius reading
■Sim. walnut case - AC wall adapter incl.
■Size: 3-1 /4"H x6-5/8”Wx 1 3/8"D

JE300 $39.95

DISCRETE LEDS

5/SI

4/SI

5/S1

4/S1

4/SI

4/S1

5/S1

4/$1

TIMEX TIOOI

LIQUID CRYSTAL DISPLAY
CLASS II

FIELD EFFECT

PM 4 ZZZ

88:88

4 DIGIT - .5" CHARACTERS
THREE ENUNCIATORS
2.00'' X 1.20'' PACKAGE
INCLUDES CONNECTOR

TIOOI-Transmissive $7.95

T1001 A-Reflective 8.25

DISPLAY LEDS

MAN 4
MAN 7G
MAN 7Y
MAN 72
MAN 74
MAN 82
MAN 84
MAN 3620
MAN 3630
MAN 3640
MAN 4610
MAN 4640
MAN 4710
MAN 4730
MAN 4740
MAN 4810
MAN 4840
MAN 6610
MAN 6630
MAN 6640
MAN 6650
MAN 6660
MAN 6680
MAN 6710

POLARITY 1

Common Anode-red
5 x 7 Dot Matrix-red
Common Cathode-red
Common Cathode-red
Common Anode-green
Common Anode-yellow
Common Anode-red
Common Cathode-red
Common Anode-yellow
Common Cathode-yellow
Common Anode -orange
Common Anode-orange ± 1
Common Cathode-orange
Common Anode-orange
Common Cathode-orange
Common Anode-red
Common Anode-red s 1
Common Cathode-red
Common Anode -yellow
Common Cathode-yellow
Common Anode-orange-D D.
Common Anode -orange ± 1
Common Cathode-orange-D.O
Common Cathode-orange ± 1 .
Common Anode -orange
Common Cathode-orange
Common Anode-red-D.D.

TYPE

MAN 6730

MAN 6740

MAN 6750

MAN 6760

MAN 6780

DL701

DL704

DL707

DL728

DL741

DL746

DL747

DL749

DL750

DL338

FN070

FND358

FND359

FND5C3

FND507

5082-7730

HDSP-3400

HOSP-3403

5082-7300

5082-7302

5082-7304

5082-7340

POLARITY

Common Anode-red ± 1
Common Cathode-red -0.D.
Common Cathode-red ± 1
Common Anode-red
Common Cathode-red
Common Anode-red r 1
Common Cathode-red

Common Cathode-red

Common Anode-red ♦ 1 .630

Common Anode-red .600

Common Cathode-red + 1 .630

Common Cathode-red 600

Common Cathode -red .110

Common Cathode .250

Common Cathode ± 1 .357

Common Cathode .357

Common Cathode(FN0500) 500

Common Anode (FND510) .500

Common Anode-red .300

Common Anode-red .800

Common Cathode red .800

4 x 7 sgl. D.git-RHOP .600

4 x 7 Sgl. Oigit-LHDP .600

Overrange character (±1) .600

4x7 Sgl. Digit-Hexadecimal .600

1.30

2.10

19.95

15.00

22.50

RCA LINEAR

CA3013T

CA2023T

CA3035T

CA3039T

CA3046N

CA3059N

CA3060N

CA3080T

CA3061N

2.15 CA3082N
2.56 CA3083N
2.48 CA3086N

1.35 CA3089N
1.30 CA3130T
3.25 CA3140T
3.25 CA3160T
85 CA3401N
2.00 CA3600N

CALCULATOR

CLOCK CHIPS

CHIPS/DRIVERS

MM5309

$4.95

MM5725

$2.95

MM5311

4.95

MM5738

2.95

MM5312

4.95

DM8864

2.00

MM5314

495

DM8865

1.00

MM5316

6.95

DM8887

.75

MM5318

9.95

DM8889

.75

MM5369

2.95

9374 7 seg.

MM5387/1998A

4 95

C.A. LED driver

1.50

MM5841

995

MC1408L7

MC1408L8

MC1439L

MC3022P

MC3061P

MC4016<74416)

MC4024P

MC4040P

MC4044P

$4.95

5.75

295

3.50

7.50

3.95

6.95

4.50

8 pin LP
14 pin LP
16 pin LP
18 pin LP
20 pin LP

14 pin ST
16 pin ST
18 pm ST
24 pin ST

16 pin SG
18 pin SG

8 pin WW
10 pin WW
14 pin WW
16 pin WW
18 pin WW

25-49

.16

50-100

.25

1-24

22 pin LP $ 37
24 pin LP 38
28 pin LP 45
36 pm LP 60

30 SOLDERTAIL STANDARD (TIN) 40 63

28 pin ST $ 99
36 pin ST 1.39
40 pin ST 159

SOLDERTAIL STANDARD (GOLD)

24 pin SG $ -TO

.24

.37

WIRE WRAP SOCKETS
(GOLD) LEVEL #3

28 pin SG 1-10
36 pin SG 1-65
40 pin SG 1-75

22 pin WW $ ,95
24 pin WW 1.05
28 pin WW 1.40
36 pin WW 1.59
40 pin WW 1.75

25-49

.36

.90
1.26
I 45

1.00

1.40

1.58

1.25
1 45
1.55

.85

1.10

1.30

1/4 WATT RESISTOR ASSORTMENTS -5%

10 OHM 12 OHM 15 OHM 18 OHM

27 OHM 53 OHM 39 OHM 47 OHM 56 OHM

68 OHM 82 OHM 100 OHM 120 OHM 150 OHM

180 OHM 220 OHM 270 OHM 330 OHM 390 OHM

470 OHM 560 OHM 680 OHM 820 OHM IK
2.2K

1.2K

8.2K

1.5K

3.9K

10K

180K

470K

1.2M

3.3*/

4.7K

220K

560K

5.6K

100k

270K

2.7K

6.8K

120K

330K

820K

2.2M

ASST. 7 5 ea

ASST. 8R Includes Resistor Assortments 1-7 (350 PCS.)

$1.75

1.75

so pcs 1.75
$9.95 ea.

50 PCS
50 PCS

$10.00 Min. Order — U.S. Funds Only Spec Sheets — 25d

Calif. Residents Add 6% Sales Tax 1979 Catalog Available - Send AM stamp

Postage- Add 5%plusS1 Insurance (if desired)

PHONE
ORDERS
WELCOME
( 415 ) 592-8097

* B

«S»-

lameco

ELECTRONICS

MAIL ORDER ELECTRONICS - WORLDWIDE

1021 HOWARD AVENUE. SAN CARLOS. CA 94070

ADVERTISED PRICES GOOD THRU OCTOBER

AY-5-9100

AY-5-9200

AY-5-9500

AY-5-2376

HD0165

74C922

TELEPHONE/KEYBOARD CHIPS

Push Button Telephone Dialler
Repertory Dialler
CMOS Clock Generator
Keyboard Encoder (86 keys)

Keyboard Encoder (16 keys)

$14. _
14.95

4.95

14.95

7.95

5.95

1 CM CHIPS

24.95

ICM7045

CMOS Precision Timer

ICM7205

CMOS LED Stopwatch/Timer

19.95

ICM7207

Oscillator Controller

7.50

ICM7208

Seven Decade Counter

1995

ICM7209

Clock Generator

6.95

NMOS READ ONLY MEMORIES

MCM6571

128 X 9 X 7 ASCII Shifted with Greek

13.50

MCM6574

128 X 9 X 7 Math Symbol & Pictures

13.50

MCM6575

128 X 9 X 7 Alphanumeric Control
Character Generator

13.50

TL074CN

TL494CN

TL496CP

11C90

95H90

4N33

MK50240

DS0026CH

TIL308

MM 5320

MM5330

LD110/111

MISCELLANEOUS

Quad Low Noise bi-fet Op Amp

Switching Regulator
Single Switching Regulator
Divide 10/11 Prescaler
Hi-Speed Divide 10/11 Prescaler

2.49

4.49
1.75

19.95

11.95
3.95

17.50

3.75

.27" red num. display w/integ. logic chip 10.50
TV Camera Sync. Generator 14.95

4 Vi Digit DPM Logic Block (Special) 3.95.

3Vi Digit A/D Converter Set 25.00/set

Photo-Darlington Opto-lsolator
Top Octave Freq. Generator
5Mhz 2-phase MOS clock driver

LITRONIX ISO-LIT 1

Photo Transistor Opto-lsolator
(Same as MCT 2 or 4N25)

2/990

SN 76477

SOUND GENERATOR
Generates Complex Sounds
Low Power - Programmable

3.95 each

TV GAME CHIP AND CRYSTAL

AY-3-8500-1 and 2.01 MHZ Crystal (Chip & Crystal _ n _ . .

includes score display. 6 games and select angles, etc. / . jQ/SBI

XR205 $8.40

XR210 4.40

XR215 4.40

XR320 1.55

XR-L555 1.50

XR555 . 39

XR556 .99

XR567CP .99
XR567CT 1.25
XR1310P 1.30
XR1468CN 3 85
XR1488 1 39

XR1489 1.39

EXAR

JE2206KA 14.95
JE2206KB 19.95
XR1800 3.20

XR2206 4.40

XR2207 3.85

XR2208 5.20

XR2209 1.75

XR2211 5.25

XR2212 4.35

XR2240 3 45

XR2242CP

XR2264

XR2556

XR2567

XR3403

XR4136

XR4151

XR4194

XR4202

XR4212

XR4558

XR4739

XR4741

1.50

4.25
3.20
2.99

1.25
1.25
2.85
4. to
3.60
2.05

.75

1.15

1.47

TYPE

DIODES

VOLTS W

PRICE

TYPE

1N4002

1N4003

VOLTS W

100 PIV 1 AMP
200 PIV 1 AMP

PRICE

12/1.00

1N746

3.3

400m

4/1.00

1N4004

400 PIV 1 AMP

12/1.00

1N751

5.1

400m

4/1.00

1N40O5

600 PIV 1 AMP

10/1 00

1N752

400m

4/1.00

1N40C6

800 PIV 1 AMP

10/1 00

1N753

6.2

400m

4/1.00

1N4007

1000 PIV 1 AMP

10/1.00

1N754

5 S

400m

4/1.00

1N3600

50 200m

6/1.00

IN757

9.0

400m

4/1.00

1N4148

75 10m

15/1.00

1N759

120

400m

4/1.00

1N4154

35 10m

12/1 00

1N959

8.2

400m

4/1.00

1N4305

75 25m

15/1.00

1N965

400m

4/1.00

1N4734

5.6 1w

1N5232

5.6

500m

1N4735

6.2 1w

1N5234

6.2

500m

1N4736

6.8 1w

1N5235

6.8

500m

1N4738

8 2 1w

1N5236

7.5

500m

1N4742

12 1w

1N5242

500m

1N4744

15 1w

1N5245

500m

INTI 83

50 PIV 35 AMP

1.60

1N456

40m

6/1.00

INI 184

100 PIV 35 AMP

1.70

1N458

150

6/1.00

1N1185

150 PIV 35 AMP

1.70

1N485A

180

10m

S/1.00

INI 186

200 PIV 35 AMP

1.80

1N4001

50 PIV 1 AMP

12/1.00

INI 188

400 PIV 35 AMP

3.00

SCR AND FW BRIDGE RECTIFIERS

C360 ISA <§ 400V SCR(2N1849)

C38M 3SA (q 600 V SCR

2N2328 1.6A (a 300V SCR

MDA 980-1 12A Cu 50V FW BRIDGE REC.

MPA 980-3 12A (a 200V FW BRIDGE REC.

C106B1

MPSA05

MPSA06

TIS97

TIS98

40409

40410
40673
2N918
2N2219A
2N2221A
2N2222A
PN2222 Plastic
2N2369
2N2369A
MPS2369
2N2484
2N2906
2N2907

PN2907 Plastic

2N2925

MJE2955

.50
30
5/1.00
6/1.00
6/1.00
1.75
1.75
1.75
4/1.00
2/1.00
4/1.00
5 ■ M
7/1 00
5/1.00
4/1.00
5/1.00
4/1.00
4/1.00
5/1.00
7/1.00
5/1.00
1 25
2/1.00

(a 200V

TRANSISTO

$1.95

1.95

2N3055

MJE3055

2N3392

2N3398

PN3567

PN3568

PN3569

MPS3638A

MPS3702

2N3704

MPS3704

2N3705

MPS3705

2N3706

MPS3706

2N3707

2N3711

2N3724A

2N3725A

2N3772

2N3823

2L.

1.00
5/1 .00
5/1.00
3/1.00
4/1.00
4/1.00
5/1.00
5/1.00
5/1.00
5/1.00

2N3904
2 N 3905
2N3906
2N4013
2N4123
PN4249
PN4250
2N4400
2N4401
2N4402
2N4403
2N4409

5/1.00 2N5086

5/1.00 2N5087

5/1 00 2N5088

5/1.00 2N5089

,.65 PN5138
1.00 2N5139
2.25 2N5210

CAPACITOR

2N5449

4/1.00
4/1.00
4/1.00
3/1.00
6/1.00
4/1.00
4/1.00
4/1.00
4/1.00
4/1 .00
4/1 00
5/1.00
4/1.00
4/1.00
4/1.00
4/1 00
5/1.00
5/1.00
5/1.00
5/1.00
5/1.00
3/1.00
3/1 00

10 pf
22 pf
47 pi
100 pf
220 pi
470 Of

001ml
.0022
0047mf
.01 mf

1/35V
15/35V
-22/35V
.33/35V
47/35V
68 /35V
1.0/35 V

47/50V
1 0/50V

3 3/50V

4 7/25 V
10/25V
10/50V
22/25 V
22/50V
47/25V
47/50V
100/25V
100/50V
220/2SV
220/50V
470/25V
1000/16V
2200/16V

VOLT CERAMIC
OISC CAPACITORS

1_3 10-99 100-

.05 04 .03 .OOluF

.05 .04

CORNER

.OW

.05 04 03 022/xF

.05 04 03 047/jF 06

05 04 . 035 ImF 12

100 VOLT MYLAR FILM CAPACJTORS
.12 .10 .07 022mf 13

.12 .10 . 07 047mf .21

12 .10 .07 1m» .27

.12 .10 07 22ml 33

+20% DIPPED TANTALUMS ISOLID) CAPACITORS
.28 . 23 .17 1.5/35V .30

.28 . 23 .17 2.2/25V .31

28 .23 .17 3.3/25V .31

.28 .23 .17 4.7/25V 32

28 . 23 17 6.8/25V .36

• 17 15/25V 63

05 035

05 04 . 035

05 .04 .035

.23 .17

.24 .20 .18

.35
32

47/25V

47/50V

1.0/16V

1.0/25V

1.0/50V

4.7/16V

4.7/2SV

4.7/50V

10/16V

10/25V

10/50V

100/25V

100/50V

220/16V

470/25V

202 Microcomputing, October 1979

Transistor Checker

— Completely Assembled —

— Battery Operated —

The AS I Transistor Checker is cap-
able of checking a wide range of
transistor types, either "in circuit"
or out of circuit. To operate,
simply plug the transistor to be
checked into the front panel
socket, or connect it with the alli-
gator clip test leads provided.
The unit safely and automatically
identifies low, medium and high-
power PNP and NPN transistors.
Size: 3%" x 654" x 2"

"C" cell battery not included.

Trans-Check S 1 9,95 eg.
Custom Cables & Jumpers

<w\

1 ■

DB 25 Series Cables

Part No.

Cable Length Connectors

Price

DB25P-4-P

4 Ft. 2-DP25P

$15.95 ea.

DB25P-4-S

4 Ft. 1 -DP25P/1 -25S

$16.95 ea

DB25$-4-S

4 ft. 2-DP25S

$17.95 ea.

Dip Jumpers

DJ14-1

1ft. 1-14 Pin

$1 .59 ea.

DJI 6-1

1 ft. 1 16 Pin

1.79 ea.

DJ24-1

1 ft. 1-24 Pin

2.79 ea.

DJ14-1-14

1 ft. 2-14 Pin

2.79 ea.

DJ16-1-16

1 ft. 2-16 Pin

3.19 ea.

DJ24-1-24

1 ft. 2-24 Pin

4.95 ea.

f ForJ|ustorTHjable^JurTi|>e^

CONNECTORS

25 Pin-D Subminiature

DB25P (as pictured) PLUG (Meets RS232) $2.95

DB25S SOCKET (Meets RS232) $3.50

DB51 226-1 Cable Cover for DB25P or DB25S $1 .75

PRINTED CIRCUIT EDGE-CARD

156 Spacing -Tin -Do ubl« Road-Out — Bituracted Contacts — Fits 054 to 070 P.C. Cards

15/30 PINS (Solder Eyelet) $1.95

18/36 PINS (Solder Eyelet) $2.49

22/44 PINS (Solder Eyelet) $2.95

50/100 (.100 Spacing) PINS (Wire Wrap) $6.95

50/100 (.125 Spacing) PINS (Wire Wrap) R681-1 $6.95

4-Digit Clock Kit

* Bright .357" ht. red display

* Sequential flashing colon

* 12 or 24 hour operation

* Extruded aluminum case (black)

* Pressure switches for hours, minutes & hold functions

* Includes all components, case and wall transformer

* Size: 3V» x 1V« x 1U

JE730 $14.95

Jumbo 6-Digit Clock Kit

* Pour .630”ht. and two .30O"ht.
common anode displays

* Uses MMS314 clock chip

* Switches for hours, minutes and hold functions

* Hours easily viewable to 30 feet

* Simulated walnut case

* 115 VAC operation

* 12 or 24 hour operation

* Includes all components, case and wall transformer

* Size: 5% x 3Vh x 1%

JE747 $29.95

• Bright .300 ht. comm, cath-
ode display

• Uses MM5314 clock chip

• Switches for hours, minutes
and hold modes

• Hrs. easily viewable to 20 ft.

• Simulated walnut case

• 115 VAC operation

• 12 or 24 hr. operation

• Incl. all components, case &
wall transformer

• Size: 654" x 3-1/8" x 154"

JE701

6-Digit Clock Kit $19.95

REMOTE CONTROL
TRANSMITTER & RECEIVER

e TRANSMITS •(TWEEN »KM« AND 41 la*

« THOUSANDS Of IKS f DR RlMTl CONTROL
AffllCATlONS

e TRANSMIT TIN UUS A 1 1V IATTI ftV
• SCHEMATIC IMCt UOt 0

Digital Stopwatch Kit

* Use Intersil 7205 Chip

* Plated thru double-sided P.C. Board

* LED display (red)

* Times to 59 min. 59.59 sec. with auto reset

* Quartz crystal controlled

* Three stopwatches in one: single event, split
(cummulative)&taylor (sequential timing)

* Uses 3 penlite batteries

* Size: 4.5" x 2.15" x .90"

JE900 $39.95

MICROPROCESSOR COMPONENTS

8 000 A
8212
8214
8216
8224
8226
8228
823B
8251
8253
8255
8257
8259

— 8080A/8080A SUPPORT DEVICES—

CPU

8-Bit Input/Output
Priority Interrupt Control
Bi-Directional Bus Driver
Clock Generator/Driver
Bus Driver

System Controller/Bus Driver

System ControBer

Prog. Comm. 1/0 (USART)

Prog Interval Timer
Prog. Periph. 1/0 (PPI)

Prog 0MA Control
Prog. Interrupt Control

S 9.95
3.25

5.95
349

3.95
3.49

5.95

7.95

14.95
995

19.95
19.95

-MICROPROCESSOR MANUALS -

M-Z80 User Manual
M-COP1802 User Manual
M-2650 User Manual

$7.50

7.50

5.00

-6800/6800 SUPPORT DEVICES

MC6800

MPU

$14.95

MC6802CP

MPU with Clock and Ram

24.95

MC6810API

128X8 Static Ram

5.95

MC6821

Periph. Inter. Adapt (MC6820)

7.49

MC6828

Priority Interrupt Controller

12.95

MC6830L8

1024X8 Bit ROM (MC68A30-8)

14.95

MC6850

Asynchronous Comm. Adapter

795

MC6852

Synchronous Serial Data Adapt

9.95

MC6860

0-600 bps Digital MODEM

12.95

MC6862

2400 bps Modulator

14.95

MC6880A

Quad 3-State Bus. Trans. (MC8T26)

2.25

MICROPROCESSOR CHIPS— MISCELLANEOUS

Z60f780C)

CPU

SI 9.95

Z80A(780-1)

CPU

24 95

CDP1802

CPU

19.95

2650

MPU

19.95

6502

CPU

11 95

8035

8-Bit MPU w/dock. RAM. 1/0 lines

19.95

P8065

CPU

19.95

TMS9900JL

16-Bit MPU w/haroware, multiply
& divide

49.95

MM500H

Dual 25 Bit Dynamic

$.50

MM503H

Dual 50 Bit Dynamic

.50

MM504H

Dual 16 Bit Static

.50

MM506H

Dual 100 Bit Static

.50

MM510H

Dual 64 Bit Accumulator

.50

MM5016H

500/512 Bit Dynamic

2504T

1024 Dynamic

3 95

2518

Hex 32 Bit Static

495

2522

Dual 132 Bit Static

2.95

2524

512 Static

2525

1024 Dynamic

295

2527

Dual 256 Bit Static

2.95

2528

Dual 250 Static

4.00

2529

Dual 240 Bit Static

4.00

2532

Quad 60 Bit Static

2.95

2533

1024 Static

2.95

3341

Filo

6.95

74LS670

4X4 Register File (TriState)

249

A-Y-5-1013

30K BAUD

5.95

2513(2140)

2513(3021)

2516

MM5230N

Character Generator (upper case)
Character Generatorjlower case)
Character Generator
2048-Bit Read Only Memory

$9.95
9.95
10 95
1 95

1101

256X1

Static

$1.49

1103

1024X1

Dynamic

2101(8101)

256X4

Static

3.95

2102

1024X1

Static

1.75

21L02

1024X1

Static

1.95

2111(8111)

256X4

Static

3.95

2112

256X4

Stalic MOS

4.95

2114

1024X4

Static 450ns

995

2114L

1024X4

Static 450ns low power

10.95

2114-3

1024X4

Slabc 300ns

1095

2114L-3

1024X4

Static 300ns low power

11 95

5101

256X4

Static

795

5280/2107

4096X1

Dynamic

495

7489

16X4

Static

1.75

74S200

256X1

Static Tristate

4.95

93421

256X1

Static

2.95

UP0414

Dynamic 16 pin

4.95

(MK4027)

UPD416

16K

Dynamic 16 pin

9.95

(MK4116)

TMS4044-

Static

14.95

45NL

TMS4045

1024X4

Static

14.95

2117

16,384X1

Dynamic 350ns

995

MMS262

2KX1

(house marked)
Dynamic

4/1.00

1702A

2048

FAMOS

$5.95

2716INTEL

16K*

EPROM

59.95

TMS2516

16K*

EPROM

49 95

(2716)

•Requires single +5V power supply

TMS2532

4KX8

EPROM

89.95

2708

EPROM

10.95

2716 T.l

16K-

EPROM

29.95

5203

"Requires 3 voltages, — 5V. +5V. +12V
2048 FAMOS

6301-1(7611) 1024
6330-1(7602) 256
82S23 32X8
82S115 4096
82S123 32X8
74186 512
74188 256
74S287 1024

Instate Bipolar
Open C Bipolar
Open Collector
fcipo ar
Tristate

TTL Open Collector
TTL Open Collector
Static

14.95
3 49

2.95
395
1995
395

9.95

3.95

2.95

CONTINENTAL SPECIALTIES

Proto Board 203 Proto Board 203/\

9 VI « SVW x 2VH

PB 203

* 75.00

Number
PB-6
PB -1 00
PB-101

LlWxH

I Inches) Price

6.0 x 4.5 X 1.4 $15.95

6.0 x 4.5 x 1.4 $19.95

6.0 x 4,5 x 1.4 $22.95

rr PB 703 P'.i
P'V tltx4lrf.lv.
provides IVHegoiitrd 5V0C supply
(seme specificmnt is PB 2031 Rip
-15VDC »nd -IS
VOC O.SA supplws. e*ct> wnh
inter nil ly ind independently adiuM-
able output voltage. Ripple and no rtf
pi + and -1SV suppim tflniV at
0.2SA.

$t24.95

PB-102

PB-103

PB-104

PB 203A

LtWiH

(Inches) Price

7.0 x 4.5 x 1.4 COS'

9.0 x 6.0 x 1.4 $44.95

9.6 x 8.0 x 1.4 $54.95

62-Key ASCII Encoder Keyboard Kit

The JE610 62-Key ASCII Encoder Keyboard
Kit can be interfaced into most any com-
puter system. The JE610 Kit comes com-
plete with an industrial grade keyboard
switch assembly (62 keys), IC's, sockets,
connector, electronic components and a
double-sided printed wiring board. The
keyboard assembly requires +5V @ 150mA
and -12V @ 10mA for operation.

FEATURES:

•60 Keys generate the full 128 char-
acters, upper and lower case ASCII
set

• Fully buffered

• 2 user-define keys provided for
custom applications

•Caps lock for upper case only
alpha characters

• Utilizes a 2376 (40 pin) encoder
read only memory chip

•Outputs directly compatible with
TTL/DTL or MOS logic arrays

•Easy interfacing with a 16-pin dip
or 18-pin edge connector

JE610 $79.95

62-Key Keyboard only. .$34.95

REGULATED POWER

JE200 5V1AMP

POWER SUPPLY

JE200 $14.95

•Uses LM309K
•Heat sink provided
•PC Board construction
•Provides a solid 1 amp
@ 5 volts

•Can supply up to ±5V,
+9V and +12V with
JE205 Adapter
• I nc ludes components,
hardware 8c instructions
•Size: 3 , /4"x5"x2"H

SUPPLY

JE205 ADAPTER BOARD

- Adapts to JE200 -
±5V, ±9V and ±12V

DC/DC converter w/
+ 5V input
•T oriodal hi-speed
switching XM F R
Short circ. protection
PC Brd. construction
Piggy back to JE200
board

'Size : 3>4”x2"x 9/1 6"h

JE205 $12.95

$10.00 Min. Order — U.S. Funds Only Spec Sheets — 25d

Calif. Residents Add 6% Sales Tax 1979 Catalog Available- Send 41d stamp

Postage- Add 5% plus $1 Insurance (if desired)

PHONE
ORDERS
WELCOME
(415) 592-8097

ameco

ELECTRONICS

MAIL ORDER ELECTRONICS - WORLDWIDE
1021 HOWARD AVENUE, SAN CARLOS, CA 94070
ADVERTISED PRICES GOOD THRU OCTOBER

The Incredible
“Pennywhistle 103 ’

$139.95

Kit Only

The Pennywhistle 103 is capable of recording data to and trom audio tape without
critical speed requirements for the recorder and it is able fo communicate directly with
another modern and terminal lor telephone ••hamming’ 1 and communications. In
addition . it is free of critical adjustments and is built with non-precision, readily available
parts

Data Transmission Method Frequency- -Shift Keying, full-duplex (half -duplex

Maximum Data Rate 300 Baud.

Data Format — Asynchronous Serial (return to mark level required

between each character).

Receive Channel Frequencies . . .2025 Hz for space. 2225 Hz for mark.

Transmit Channel Frequencies . .Switch selectable: Low (normal) = 1070 space.

1270 mark: High = 025 space. 2225 mark

-46 dbm accousticalfy coupled.

-15 dbm nominal. Adjustable from -6 dbm

to -20 dbm.

Receive Frequency Tolerance . . .Frequency reference automatically adjusls to
allow for operation between l800H7and 2400 Hz

Oigital Oata Interface EIA RS-232C or 20 mA current loop (receiver is

optoisoiated and non-polar),

Power Requirements 120 VAC. single phase. 10 Watls

Physical All components mount on a single 5* by 9"

pr nted circuit board. All components Included

Requires a VOM, Audio Oscillator. Frequency Counter and/or Oscilloscope to align.

TRS-80

16K Conversion Kit

Expand your 4K TRS-80 System to 16K. Kit
comes complete with:

• 8 each UPD416-1 (16K Dynamic Rams) 250NS

* Documentation for conversion

TRS-16K $75.00

COMPUTER CASSETTES

*6 EACH 15 MINUTE HIGH
QUALITY C-15 CASSETTES

* PLASTIC CASE INCLUDED
12 CASSETTE CAPACITY

* ADDITIONAL CASSETTES
AVAILABLE #C-15-I$2.95 ea

CAS -6

•=. 1 :JVl $14.95

( . (Case and 6 Cassettes)

SUP ’R’ MOD II

UHF Channel 33 TV Interface Unit Kit

Wide Band B/W or Color System

★ Converts TV to Video Display for
home computers, CCTV camera,
Apple II, works with Cromeco Daz-
zler, SOL-20, IRS-80, Challenger,
etc.

MOD II is pretuned to Channel 33
(UHF).

* Includes coaxial cable and antenna
transformer.

MOD II

$29.95 Kit

Function Generator Kit

• Provides 3 basic waveforms:
sine, triangle & square wave

• Frequency range from 1 Hz to
100K Hz

• Output amplitude from 0 volts to
over 6 volts (peak to peak)

• Uses a 12V supply or a ±6V split
supply

• Incl. chip, P.C. board, compo-
nents and instructions

JE2206B $19.95

IDEAL FOR TRS 80

"Plug/Jack interface to any
computer system requiring
remote control of cassette
functions"

The CC100 controls cassette
motor functions, monitors
tape location with its internal
speaker and requires no
power. Eliminates the plugging
and unplugging of cables dur-
ing computer loading opera-
tion from cassette.

CASSETTE CONTROLLER

#CC

$29.50

Micro-

Miniature

Joystick

• 2 each 100K pots (Linear Taper)

• Printed Circuit Board Mount

• Size: 1" x 1-3/16"x 1-3/16"

Micro-Miniature Joystick ...

M 95/

p* Reader Service— see page 227

Microcomputing, October 1979 203

“THE ORIGINAL"

9 Personal
C Computing

9 79

Plan Now to attend
the best Personal
Computing show ever,

Friday, Saturday, Sunday
October 5-6-7th
Philadelphia Civic Center

Philadelphia, Pa.

PC 79

Don't be confused — Other shows are copying us but
they cannot equal us. We are the Original Personal
Computing Show. Now in our Fourth Year.

FEATURING:

Major Exhibits
from the

Leading Companies

•

Personal Computing College
with 80 Hours of
Free Seminars by the
Industry's Leading Speakers

•

Major Emphasis
on

Software Exhibits

•

2nd Annual

Computer Music Festival
Bigger! Better!

•

Antique

Computing Devices
on Display

•

See All the Latest
Hardware

•

Business Systems
and

Business Software

For more information and a
Free subscription to our "PERSONAL
COMPUTING" newspaper, send
your name and address to:

PERSONAL COMPUTING 79

Rt. 1, Box 242 . Mays Landing. N.J. 08330 . 609/653-1188

Industry TRADE SHOW on October 4th
For exhibiting information please call or write.

204 Microcomputing, October 1979

10-DAY FREE TRIAL

Send for our
FREE Catalog

4K - Keyboard C $ 595

8K - Keyboard C $ 795

16K - Keyboard B $995

16K - Keyboard N $ 995

32K - Keyboard C $1195

32K - Keyboard B $1195

32K - Keyboard N $1195

C — calculator Keyboard (only version with tape deck)
B — Large Keyboard (graphics not on keys)

N — large keyboard with graphics symbols

Used 8K PET with 90-day warranty $650

WE BUY USED PET, APPLE and TBS- SO COMPUTERS

$100 FREE ACCESSORIES
WITH 16K or 32K PET

Terminal Package with 8K PETs

PET ACCESSORIES

Commodore Dual Floppy Disk Drive $1295.00

Commodore Printer (tractor feed) $995.00

Commodore Printer (friction feed) $995.00

NEW! T/C 2001 Terminal Package for the PET $69.00

Second Cassette — from Commodore $95.00

Commodore PET Service Kit $30.00

Beeper - Tells when tape is loaded $24.95

Petunia - Play music from PET $29.95

Video Buffer - Attach another CRT $29.95

Combo - Petunia and Video Buffer $49.95

Betsi 4-slot S-100 Motherboard r Uffl $119.00

S-100 PET Interface was $289 00 SALE $99.00

New Serial Printer Interface for PET $79.95

PET - Compatible Selectric in Desk $895.00

Call for Availability

Originate/Answerback Modem for PET $320.00

Bi-directional RS-232 Interface $280.00

apple II

' p/us

200 FR€€ ACCESSORIES!

The new Apple II with Applesoft BASIC built-in! Elimi-
nates the need for a $200 Firmware Card and includes I
new Autostart ROM for easy operation. This combined I
with the FREE accessories from NCE could save you up |
to $400 on a 48K Apple II system!

1 6K Apple II Plus — $1 1 95 (take $1 00 in free accessories)
32K Apple II Plus — $1345 (take $1 50 in free accessories)
48K Apple II Plus — $1495 (take $200 in free accessories)

Apple II Accessories

Centronics Printer Interface $225

Disk and Controller Call for Availability $595

Second Disk Drive $495

Parallel Printer Card . . $180

Communications Card
Hi-Speed Serial Card

Firmware Card

Hobby/Proto Card

Call for
Availability '

$225

$195

$200

$24

PET OWNERS . . .

REMOTE

TERMINAL

for

only $69

A self-contained
module and program
cassette enables your
PET to function as a
300 baud terminal,
Supports Upper/Lower
case, Rubout, Escape
& all control functions
Output is TTL

FREE

WITH PET PURCHASE

Microverter RF Mod $35

Sanyo M2544 Recorder $55

IN STOCK NOW!

EVERY ITEM IN THIS ADVERTISEMENT IS IN STOCK
AND READY TO SHIP, EXCEPT WHERE NOTED.

NOW Graphics printer
| $1,098 for Apple II

Now you can print high resolution graphics from your
Apple using the IP-225 printer and graphics option from
IDS. The IP-225 is a tractor feed printer with 96 possible
characters. Line length is 80/132 col. with a speed of
50/80 cps. We include software which allows it to use
either parallel or serial interface at 1200 baud. ABSO-
LUTELY FREE (you save $50)!

DMlrton Splertr

«0 0 #c
DISK &
MEMORY
EXPANSION

You can instantly turn
your PET into a speedy
and efficient professional
computer. Its easy with
the new 400K Disk Drive
and Memory Expansion
from Computhink Add up
to 32K internally then load
20K program in only 3
seconds!

400K Disk

Drive $1,295.00

Memory Expansion

16K $425.00

24K $525.00

.32 K $615.00

Hazeltine 14001

LIST SALE

SUPER SALE PRICE!
TOO LOW TO ADVERTISEl

Immediate Delivery — 2- Year Factory Warranty
You may have seen the Hazeltine advertised at $850. You I
may have seen it sale prices at $749 or even $699 but our
new price is so low that we can’t even advertise it. Call us
for a quote. Hurry, we have a limited quantity at this price.
The 8048-based Hazeltine 1400 has a 12" screen. 24 x 80
display. TTY-style keyboard, addressable cursor, and
RS-232 I/O from 110 to 9600 baud

Hazeltine 1510 — $1195
Hazeltine 1520 — $1499

LOW COST
PRINTER
* FOR

PET

Hazeltine 1410 — $835
Hazeltine 1500 — $1069

$395

This is a completely M»tinD>sHe<
Teletype KSR-33 teim.nai teady u
attachto your PET* . menace t<
use as a printer

IN STOCK
NOW

OF THE
MONTH

Desktop Selectrlc-Based -
Terminal $319!

Super bargain while they last: A desktop terminal
based on an IBM Selectric typewriter for only $319
including documentation. These terminals were
originally designed for use with timesharing sys-
tems where top-quality printing was required. The
IBM keyboard and printer are separated by a three
foot cable and each has its own enclosure (great for
custom installations). Serial RS-232 interface uses
PTTC instead of ASCII codes so you will need to write a
conversion program (we have no ascii interface for
this model). 14.8 cps, 134.5 baud 13" line length, pica.
Sold in AS-IS condition, our warranty is limited to
replacement of missing parts (we checkall motors).

CompuMart

SELLING COMPUTERS BY MAIL
SINCE 1971

1250 North Main Street, L)epanmentKBA9
P.0. Box 8610 Ann Arbor, Michigan 48107

(313) 994-3200 „ N7

ISANYO MONITOR

9-inch

*$* 40 .

$169

CAT
COUPLER

New 300 baud
Originate/Answer
Acoustic Coupler.

Looks good, works
great qq

priced at I 057

SANYO
MONITOR

when you buy the

SORCERER

$995

Z-80 Processor • Full-size keyboard • User definable
characters • Up to 32K on-board RAM • Interchangeable
ROM PACs • 30 x 64 display • Resident 4k monitor ROM •
Dual Cassette I/O • Serial and Parallel I/O • Complete
operator's manual

Simply add a monitor and tape decks to complete the
system. Can be used as a terminal. Microsoft BASIC
ROM PAC is standard. NEW! Exidy Word Processing
ROM PAC now available which handles tabs, search/
replace, etc., many different printers and can be used
with cassette or disk. The most flexible W/P system we’ve
ever seen.

Sorcerer 8K
Sorcerer 16K
Sorcerer 32K

Word Processing ROM PAC

$995
$1150 I
$1395

Call for Availability $99

Member:

Computer Dealers
Association

IMPORTANT ORDERING INFORMATION
All orders must include 4% shipping and handling. Michigan residents add 4%
for state sales tax. All foreign orders (except Canada) need an additional 10% for
shipping and handling.

Phones open from 9:00 a.m. to 7:00 p.m. EST Monday-Friday, 10:00 a.m. to
5:00 p.m. Saturdays • P.O.’s accepted from D & B rated companies — ship-
ment contingent upon receipt of signed purchase order • All prices
subject to change without notice • Most items in stock for immediate
shipment — call for delivery quotation • Sorry, no C.O.D.’s •

In the Ann Arbor area? Retail store open 1 1:00 a.m. to 7:00 p.m. Tuesday-
Friday, 10:00 a.m.to 5:00 p.m. Saturdays (Closed Sunday and Monday)

If not satisfied, return your purchase with-in 10 days for full
refund of purchase price!

v* Reader Service— see page 227

Microcomputing, October 1979 205

COMPUCRUISE

Put a computer in
your car, which gives
you the most effec-
tive and functional
cruise control ever
designed, plus com-
plete trip computing,
fuel management sys-
tems, and a remark-
able accurate quartz
crystal time system.
So simple a child can
operate, the new
CompuCruise com-
bines latest computer
technology with
state-of-the-art re-
liability in a package
which will not likely be
available on new cars
for years to come •
Cruise Control •Time,
E.T., Lap Timer, Alarm

• Time, Distance, Fuel
to Arrival • Time, Dis-
tance, Fuel to Empty •
Time, Distance and
Fuel on Trip • Current
or Average MPG,
GPH • Fuel Used, Dis-
tance since Fillup •
Current and Aver-
age-Vehicle Speed •
Inside, Outside or
Coolant Temperature

• Battery Voltage •
English or Metric
Display. $199.95

FLOPPY DISK
STORAGE BINDER

This black vinyl
three-ring binder
comes with ten
transparent plastic
sleeves which ac-
commodate either
twenty, five-inch or
ten, eight-inch floppy
disks. The* plastic
sleeves may be or-
dered separately and
added as needed. A
contents file is in-
cluded with each
sleeve for easy iden-
tification and organiz-
ing. Binder & 10 hol-
ders $14.95 Part No.
B800; Extra holders
95* each. Part No.
800

OPTO-ISOLATED
PARALLEL INPUT
BOARD FOR
APPLE II

There are 8 in-
puts that can be dri-
ven from TTL logic or
any 5 volt source.The
circuit board can be
plugged into any of
the 8 sockets of your
Apple II. It has a 16 pin
socket for standard
dip ribbon cable con-
nection.

Board only $15.00.
Part No. 120, with
parts $69.95. Part
Np. 120A.

TIDMA

• Tape Interface Direct
Memory Access • Re-
cord and play programs
without bootstrap load-
er (no prom) has FSK
encoder/decoder for
direct connections to
low cost recorder at
1200 baud rate, and
direct connections for
inputs and outputs to
a digital recorder at
any baud rate • S-1 00
bus compatible • Board
only $35.00 Part No.
1 1 2, with parts $110
Part No. 1 1 2A

SYSTEM

MONITOR

B080, 8085, or Z-80
System monitor for use
with the TIDMA board.
There is no need for the
front panel. Complete
with documentation
$12.95.

16K EPROM

Uses 2708 EPROMS,
memory speed selec-
tion provided, ad-
dressable anywhere in
65K of memory, can
be shadowed in 4K in-
crements. Board only
$24.95 part no.
7902, with parts less
EPROMs $49.95 part
no. 7902A.

ASCII KEYBOARD

TTL & DTL compatible • Full 67 key array

• Full 128 character ASCII output • Positive
logic with outputs resting low • Data Strobe

• Five user-definable spare keys • Standard
22 pin dual card edge connector • Requires
+5VDC, 325 mA. Assembled & Tested.
Cherry Pro Part No. P70-05AB. $135.00.

ASCII KEYBOARD

53 Keys popular ASR-33 format • Rugged
G-10 P. C. Board • Tri-mode MOS encoding
• Two-Key Rollover • MOS/DTL/TTL Compat-
ible • Upper Case lockout • Data and Strobe
inversion option • Three User Definable
Keys • Low contact bounce • Selectable Par-
ity • Custom Keycaps • George Risk Model
753. Requires +5, -12 volts. $59.95 Kit.

ASCII TO CORRESPONDENCE
CODE CONVERTER

This bidirectional board is a direct replace-
ment for the board inside the Trendata 1 000
terminal. The on board connector provides
RS-232 serial in and out. Sold only as an
assembled and tested unit for $229.95.
Part No. TA 1000C

DISK JACKET™

Made from heavy duty
.0095 matte plastic
with reinforced

grommets. The mini-
diskette version holds
two 5-1/4 inch disk-
ettes and will fit any
standard three ring
binder. The pockets to
the left of the disk-
ette can be used for
listing the contents of
the disk. Please order
only in multitudes of
ten. $9.95/10 Pack.

INTERNATIONAL

MICROPROCESSOR

DICTIONARY

English, French, Dan-
ish, German, Italian.
Hungarian, Norwe-
gian, Polish, Spanish,
Swedish. 10 lan-
guages, 28 pp.
SYBEX. Ref. IMD.
$4.95

VIDEO TERMINAL

16 lines, 64 columns •
Upper and lower case •
5x7 dot matrix •
RS-232 in • RS-232
out with TTL parallel
keyboard input • On
board baud rate
generator 75, 110,
150, 300, 600. &
1200 jumper selecta-
ble • Memory 1024
characters (7-21 L02)
• Video processor chip
SFF96364 by Necu-
lonic • Control char-
acters (CR, LF,
t, 4 , non destructive
cursor, CS, home, CL*
White characters on
black background or
vice-versa • With the
addition of a keyboard,
video monitor or TV
set with TV interface
(part no. 107A) and
power supply this is a
complete stand alone
terminal *also S-100
compatible • requires
+16, & -16 VDC at
100mA, and 8VDC at
1 A. Part no. 1000A
$199.95 kit.

RS-232/20mA

INTERFACE

This board has two
passive, opto-isola-
ted circuits. One con-
verts RS-232 to
20mA, the other con-
verts 20mA to RS-
232. All connections
go to a 10 pin edge
connector. Requires
+12 and -12 volts.
Board only $9.95,
part no. 7901, with
parts $14.95 Part
No. 7901 A.

COMPUCOLOR II

Model 3, 8K $1,395.
Model 4, 16K $1,595.

Model 5. 32K^ $1,895.

Prices include color
monitor, computer,
and one diskdrive.

PET COMPUTER

With 32K & monitor -
$1195. Dual Disk
Drive - $1195.

^cippkz

APPLE II PLUS

16K - $995, 32K -
$1059, 48K - $1123.
Disk & cont $589

6502

APPLICATIONS

BOOK

Z80 APPLICATIONS
BOOK*

This book will teach
you how to connect a
board to the outside
world and implement
practical applications
for the 6502, (or
Z80). Applications
range from home con-
trol (a complete alarm
system, including
heat sensor), to in-
dustrial applications.
You will learn tech-
niques ranging from
simulated traffic con-
trol to analog-digital
conversion. All exper-
iments can be realized
with a minimum of ex-
ternal (low-cost)
components. They are
directly applicable to
any 6502-based
board such as SYM,
KIM, AIM 65. This
book also studies in
detail input-output
techniques and com-
ponents, and is the
logical continuation of
C202 (or C280). By
Rodney Zaks.

SYBEX. 6502: Ref.
D302; Z80: Ref

D380. Each $12.95

T.V. INTERFACE

• Converts video to
AM modulated RF,
Channels 2 or 3. So
powerful almost no
tuning is required. On
board regulated power
supply makes this ex-
tremely stable. Rated
very highly in Doctor
Dobbs’ Journal. Recom-
mended by Apple •
Power required is 12
volts AC C.T., or +5
volts DC • Board only
$7.60 part No. 107,
with parts $1 3.50 Part
No. 1 07A

PARALLEL TRIAC
OUTPUT BOARD
FOR APPLE II

This board has 8 triacs capable of
switching 110 volt 6 amp loads (660 watts
per channel) or a total of 5280 watts. Board
only $15.00 Part No. 210, with parts
$119.95 Part No. 210A.

TO Order * Mention P art no - description, and price. In USA shipping paid by us for orders accompanied by check or money order. 1
IV v UG . We accept . e g g orders in the U. S. only, or a VISA or Master Charge no., expiration date, signature, phone no.,
A&j shipping charges will be added. CA residents add 6.5% for tax. Outside USA add 10% for air mail postage and han-
■NPJ: dling. Payment must be in U. S. dollars. Dealer inquiries invited. 24 hour order line (408) 226-4064.

Rand fnr FRFF Catalan a hin salf-addrassad anvalnna with 41 * nostana nats it fastest!

206 Microcomputing, October 1979

iS E21

TRS-80 ES
SERIAL I/O

• Can input into basic

• Can use LUST and
LPRINT to output, or
output continuously •
RS-232 compatible •
Can be used with or
without the expansion
bus • On board switch
selectable baud rates
of 110,150,300,600,
1 200, 2400, parity or
no parity odd or even,
5 to B data bits, and 1
or 2 stop bits. D.T.R.
line • Requires +5,
-12 VDC • Board only
$19.95 Part No. B010,
with parts $59.95 Part
No. 801 OA, assembled
$79.95 Part No. 8010
C. No connectors pro-
vided, see below.

EIA/flS-232 con-
nector Pert No.
□B25P $600. with
9'. 6 conductor

ceble SI 095 Part
No. OB25P9.

ribbon cable
with attached con-
nectors to fit TRS-
80 and our serial
board $1 9.95 Part
No 3CAB40.

RS-232/ TTL
INTERFACE

• Converts TTL to RS-
232, and converts RS-
232 to TTL • Two sep-
arate circuits • Re-
quires -12 and +12
volts • All connections
go to a 10 pin gold
plated edge connector

• Board only $4.50
Part No. 232, with
parts $7.00 Part No.
232A 10 Pin edge
connector $3.00 Part
No. 10P

MODEM

• Type 103 • Full or
half duplex • Works up
to 300 baud • Origi-
nate or Answer • No
coils, only low cost
components • TTL in-
put and output-serial

• Connect 8 H speak-
er and crystal mic.
directly to board •
Uses XR FSK demod-
ulator • Requires +5
volts • Board only
$7.60 'Part No. 109,
with parts $27.50 Part
No. 1 09A

DISKETTES

Box of 10, 5” $29.95,
8" $39.95.

Plastic box, holds 10
diskettes, 5" - $4.50,
8” - $6.50.

RS-232/TTY

INTERFACE

This board has two
active circuits, one
converts RS-232 to
20mA, and the other
converts 20mA to
RS-232. Requires
+12 and -12 volts.
Board only $4.50 Part
No. 600, with parts
$7.00 Part No. 600A.

SHIP

mtrm

S-100 BUS
ACTIVE TERMINATOR

Board only $14.95 Part No. 900, with parts
$24.95 Part No. 900A

apple ii-::-

SERIAL I/O
INTERFACE

Baud rate is continuously adjustable from 0
to 30,000 • Plugs into any peripheral
connector • Low current drain. RS-232 input
and output • On board switch selectable 5 to
8 data bits, 1 or 2 stop bits, and parity or no
parity either odd or even • Jumper selectable
address • SOFTWARE • Input and Output
routine from monitor or BASIC to teletype or
other serial printer • Program for using an
Apple II for a video or an intelligent terminal.
Also can output in correspondence code to
interface with some selectrics. • Also
watches DTR • Board only $15.00 Part No.
2, with parts $42.00 Part No. 2A, assembled
$62.00 Part No. 2C

8K EPROM PIICEON

Saves programs on PROM permanently (until
erased via UV light) up to 8K bytes. Programs
may be directly run from the program saver
such as fixed routines or assemblers. • S-
100 bus compatible • Room for 8K bytes of
EPROM non-volatile memory (2708‘s). • On-
board PROM programming • Address
relocation of each 4K of memory to any 4K
boundary within 64K • Power on jump and
reset jump option for "turnkey" systems and
computers without a front panel • Program
saver software available • Solder mask both
sides • Full silkscreen for easy assembly.
Program saver software in 1 2708 EPROM
$25* Bare board $35 including custom coil,
board with parts but no EPROMS $1 39. with
4 EPROMS $179, with 8 EPROMS $219.

WAMECO PRODUCTS
WITH

ELECTRONIC SYSTEMS PARTS

FDC-1 FLOPPY CONTROLLER BOARD will
drive shugart, pertek, remex 5" & 8" drives
up to 8 drives, on board PROM withpower
boot up, will operate with CPM (not

included). PCBD $42.95

FPB-1 Front Panel. (Finally) IMSAI size hex
displays. Byte or instruction single step.

PCBD $42.95

MEM-1 A 8Kx8 fully buffered, S-10Q, uses
2102 type RAMS.

PCBD $24.95, $168 Kit

QMB-12 MOTHER BOARD. 1 3 slot, termi-
nated, S-100 board only $34.95

$89 95 Kit

CPU-1 8080A Processor board S-1 00 with
8 level vector interrupt PCBD . . $25.95
$89.95 Kit

RTC-1 Realtime clock board. Two independ-
ent interrupts. Software programmable.

PCBD $25.95, $60.95 Kit

EPM-1 1702A 4K EPROM

card PCBD $25.95

$49.95 with parts less EPROMS
EPM-2 2708/2716 16K/32K

EPROM card PCBD $24.95

$49.95 with parts less EPROMS
QMB-9 MOTHER BOARD. Short Version of

QMB-12. 9 Slots PCBD $30.95

$67.95 Kit

MEM-2 1 6Kx8 Fully Buffered 2114 Board
PCBD $25.95, $269.95 Kit

T.V.

TYPEWRITER

• Stand alone TVT

• 32 char/line, 16
lines, modifications for
64 char/line included

• Parallel ASCII (TTL)
input • Video output

• 1 K on board memory

• Output for computer
controlled curser •
Auto scroll • Non-
destructive curser #
Curser inputs: up, down,
left, right, home, EOL
EOS • Scroll up, down

• Requires +5 volts
at 1.5 amps, and -1 2
volts at 30 mA • All
7400, TTL chips •
Char. gen. 2513 •
Upper case only •
Board only $39.00
Part No. 106, with
parts $145.00 Part
No. 1 06A

UART &
BAUD RATE
GENERATOR

• Converts serial to
parallel and parallel to
serial • Low cost on
board baud rate gener-
ator • Baud rates:
110, 150, 300, 600,
1200, and 2400 •
Low power drain +5
volts and -12 volts
required • TTL com-
patible • All characters
contain a start bit, 5
to 8 data bits, 1 or 2
stop bits, and either
odd or even parity. • All
connections go to a 44
pin gold plated edge
connector • Board only
$12.00 Part No. 101,
with parts $35.00 Part
No. 101 A, 44 pin edge
connector $4.00 Part
No. 44P

TAPE
INTERFACE

• Play and record Kan-
sas City Standard tapes

• Converts a low cost
tape recorder to a
digital recorder • Works
up to 1 200 baud • Dig-
ital in and out are TTL-
serial • Output of
board connects to mic.
in of recorder • Ear-
phone of recorder con-
nects to input on board

• No coils • Requires
+5 volts, low power
drain • Board only
$7.60 Part No. Ill,
with parts $27.50 Part
No. 1 1 1 A

HEX ENCODED

KEYBOARD

E.S.

This HEX keyboard
has 1 9 keys, 1 6 encod-
ed with 3 user defin-
able. The encoded TTL
outputs, 8-4-2-1 and
STROBE are debounced
and available in true
and complement form.
Four onboard LEDs
indicate the HEX code
generated for each
key depression. The
board requires a single
+5 volt supply. Board
only $15.00 Part No.
HEX-3, with parts
$49.95 Part No. HEX-
3A. 44 pin edge con-
nector $4.00 Part No.
44 P.

DC POWER SUPPLY

• Board supplies a regulated +5
volts at 3 amps., +1 2, -1 2, and -5
volts at 1 amp. • Power required is
8 volts AC at 3 amps., and 24 volts
AC C.T. at 1.5 amps. • Board only
$12.50 Part No. 6085, with parts
excluding transformers $42.50
Part No. 6085A

Tq Qr/jgr . Mention part no. description, and price. In USA shipping paid by us for orders accompanied by check or money order. 1
v ' We accept C.O.D. orders in the U. S. only, or a VISA or Master Charge no., expiration date, signature, phone no.,
shipping charges will be added. CA residents add 6.5% for tax. Outside USA add 10% for air mail postage and han-
dling. Payment must be in U. S. dollars. Dealer inquiries invited. 24 hour order line (408) 226-4064.

RpnH fr»r FRFF Hatalnn p hin cplf-pHHrpQ<;pH pnvplnnp with 41 * nndtpnp nptQ it fpctpctl

*>E21

iS Reader Service— see page 227

Microcomputing, October 1979 207

: : :

16K EPROM CARD-S 100 BUSS

~V 8K LOW POWER RAM KIT-S 100 BUSS

250 NS SALE! . _

'ADD $5
FOR
250NS!

OUR

BEST

SELLING

KIT!

USES 2708’s!

Thousands of personal and business systems around
the world use this board with complete satisfaction.
Puts 16K of software on line at ALL TIMES! Kit features
a top quality soldermasked and silk-screened PC board
and first run parts and sockets. All parts (except 2708’s)
are included. Any number of EPROM locations may be
disabled to avoid any memory conflicts. Fully buffered
and has WAIT STATE capabilities.

OUR 450NS 2708’S
ARE $8.95 EA. WITH
PURCHASE OF KIT

ASSEMBLED
AND FULLY TESTED
ADD $25

$129

KIT

(450 NS RAMS!)

Thousands of computer systems rely on this rugged, work
horse, RAM board. Designed for error-free, NO HASSLE,
systems use.

KIT FEATURES:

Doubled sided PC Board with solder
mask and silk screen layout. Gold
plated contact fingers.

2. All sockets included.

3. Fully buffered on all address and data
lines.

4. Phantom is jumper selectable to pin
67.

5. FOUR 7805 regulators are provided

>/ V on card.

Blank PC Board w/Documentation

$29.95

Low Profile Socket Set. .13.50
Support IC’s (TTL & Regulators)

$9.75

Bypass CAP’S (Disc & Tantalums)

$4.50

ASSEMBLED AND FULLY
BURNED IN ADD $30 A

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*••••4

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16K STATIC RAM KIT-S 100 BUSS

$ 279

KIT

PRICE CUT!

FULLY
STATIC, AT
DYNAMIC PRICES

WHY THE 2114 RAM CHIP?

We feel the 21 1 4 will be the next industry standard
RAM chip (like the 2102 was) This means price,
availability, and quality will all be good! Next, the
2114 is FULLY STATIC! We feel this is the ONLY
way to go on the S-100 Buss! We’ve all heard the
HORROR stories about some Dynamic Ram
Boards having trouble with DMA and FLOPPY
DISC DRIVES. Who needs these kinds of
problems? And finally, even among other 4K
Static RAM's the 21 1 4 stands out! Not all 4K static
Rams are created equal! Some of the other 4K's
have clocked chip enable lines and various timing
windows just as critical as Dynamic RAM’s. Some
of our competitor’s 16K boards use these "tricky"
devices But not us! The 21 14 is the ONLY logical
choice for a trouble-free, straightforward design

KIT FEATURES:

1. Addressable as four separate 4K Blocks.

2. ON BOARD BANK SELECT circuitry.
(Cromemco Standard!). Allows up to 512K on
line!

3. Uses 2114 (450NS) 4K Static Rams

4 ON BOARD SELECTABLE WAIT STATES.

5. Double sided PC Board, with solder mask and
silk screened layout. Gold plated contact fingers.

6. All address and data lines fully buffered.

7. Kit includes ALL parts and sockets.

8. PHANTOM is jumpered to PIN 67.

9. LOW POWER: under 2 amps TYPICAL from the
t8 Volt Buss

10 Blank PC Board can be populated as any
multiple of 4K.

BLANK PC BOARD W/DATA— $33

LOW PROFILE SOCKET SET-$12 ASSEMBLED & TESTED-ADD $30

SUPPORT IC’S & CAPS— $19.95

2114 RAM’S— 8 FOR $69.95

16K STATIC RAM SS-50 BUSS

$ 295

KIT

FULLY STATIC
AT DYNAMIC PRICES

KIT FEATURES:

FOR SWTPC
6800 BUSS!

ASSEMBLED AND
TESTED - $30

Addressable on 16K Boundaries

2. Uses 2114 Static Ram

3. Runs at Full Speed

4. Double sided PC Board. Solder
mask and silk screened layout.
Gold fingers.

5. All Parts and Sockets included

6. Low Power: Under 2 Amps

Typical

BLANK PC BOARD— $33

COMPLETE SOCKET SET— $12

yv_

SUPPORT IC’S AND CAPS-$19.95

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TM990 BUSS PROTOTYPE & WIREWRAP BOARD

For use with the Texas Instrument Series of 16 Bit
Microcomputer Modules. Fully buss compatible. An
inexpensive and quick way to expand the capacity
of your Tl computer. Made of G-10 Epoxy PC
material. Gold plated contact fingers all plated
through holes. High density, up to over 100 DIP’S.
Fully documented. $70 each (OEM Discounts Available)
Z-80 PROGRAMMING MANUAL

By MOSTEK, orZILOG. The most detailed explanation
ever on the working of the Z-80 CPU CHIPS. At least
one full page on each of the 158 Z-80 instructions. A
MUST reference manual for any user of the Z-80. 300
pages. Just off the press. $12.95

PROC. TECH. QUITS THE MICROPROCESSOR BUSINESS!
FACTORY CLOSE OUT - SPECIAL PURCHASE!
#16KRA

16K S-100 Dynamic Ram Board - $149. 95

ORIGINALLY PRICED AT $429 each!

We purchased the remaining inventory of PT’s popular
16K Ram Board when they recently closed their plant.
Don’t miss the boat! These are brand new, fully tested,
ASSEMBLED and ready to go. All are sold with our
standard 90 day limited warranty!!

72 Page Full Manual, Included Free!

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NOT ASSOCIATED WITH DIGITAL RESEARCH OF CALIFORNIA, THE SUPPLIERS OF CPM SOFTWARE.

Digital Research: Computers

® (OF TEXAS) r

P.O. Box 401565 • GARLAND, TEXAS 75040 • (214) 494-1505

TERMS: Add 50<t postage, we pay balance Orders under $15 add 75<t handling.
No C O D. We accept Visa. MasterCharge. and American Express cards. Tex.
Res. add 5% Tax. Foreign orders (except Canada add 20% P & H. 90 Day Money
Back Guarantee on all items

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• P J» •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••#

•••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• ••••••**

You can't beat our prices . . .

nor can you beat our delivery!

NORTH STAR HORIZON CPU BOARDS VIDEO TERMINALS

NOW DOUBLE- & QUAD-DENSITY

HORIZON 1 -

16K, D-D, Kit, List $1599 $1349

16K.D-DA&T, List $1899 1599

32K, D-D, Kit, List $1849 1559

32K, D-D, A&T, List $2099 1779

32K, Q-D, A&T, List $2349 1994

HORIZON 2 -

16K, D-D, Kit, List $1999 $1699

16K, D-D, A&T, List $2349 1939

32K, D-D, A&T. List $2249 1909

32K, D-D, A&T, List $2549 2159

32K, Q-D. A&T. List $2999 2539

TRS-80 and interfaces
- LESS 10% -

CROMEMCO SYSTEMS

SYSTEM 3 - Features 4 MHz CPU, 32K of
RAM, dual PerSci floppy disk drive (and
provision for installing 2 additional drives),
RS232 interface, printer interface, A&T,

ready to use, List $5990 . . . ONLY $4990
64 K Version, List $6585 $5485

SYSTEM 2, similar to System 3 but features
dual minifloppies, A&T, List $3990 . $3390

Z-2 COMPUTER SYSTEM, for rack-mount-
ing, Z80 processor, 21 slots, P.S., front
cover panel, A&T, List $995 $845

Z-2D DISK COMPUTER, similar to Z-2 but
comes w/floppy disk controller, DOS, &
minifloppy disk drive. A complete system
w/addition of RAM board, A&T, $1689

FLOPPY DISK SYSTEMS

MORROW THINKER TOYS® Discus 2D,

List $1149 OUR PRICE $979

Discus 2D, dual-drive, List $1948 $1658

MICROMATION Megabox, double-density
w/8" drives. List $2295 $2054

MICROPOLIS 1041 MacroFloppy® in
enclosure (power source & regulator board

required), List $695 $625

1042 MacroFloppy w/case & AC P.S. . $709
1053 Dual MetaFloppy®, List $1895 . $1695

CONVERT YOUR SELECTRIC
TO A COMPUTER PRINTER!

Power supply & electronics, A&T. You make
only a simple solenoid installation (or have
the factory do it). Manufactured by ESCON.
S-100 Interface Version, List $496 . $445
Universal Types:

Parallel — (Centronics format, for TRS-80,
Sorcerer, Apple, etc.) List $525 . . . $469
IEEE-488 (for PET), List $560 . . . $499
RS232 Standard Serial, List $549 $489

NORTH STAR Z80A Processor Board

Kit (ZPB-A), List $199 $169

A&T (ZPB-A/A), List $259 $209

CROMEMCO 4MHz CPU Card

Kit (ZPU-K), List $295 $250

A&T (ZPU-W), List $395 $335

CROMEMCO 4 MHz Single Card Computer

(SCC-K) Kit, List $395 $335

A&T. List $450 $382

VECTOR GRAPHIC Z-80 CPU Board

A&T, List $215 $184

ITHACA AUDIO Z-80 CPU Board, 4 MHz

A&T, List $205 $179

2 MHz, A&T, List $175 $155

DELTA Z-80 CPU with I/O, A&T . . . $289

XITAN ZPU-1 Kit . . . $129

SD Single Card Computer (SBC-100)

Kit, List $239 $210

A&T, List $369 $329

MEMORY BOARDS

DYNABYTE, A&T — full 1 -year warranty
16K Static RAM Module, 250ns . . . $359
32K Static RAM Module, 250ns ($995) $796
NORTH STAR 16K Dynamic RAM Board,

Kit (RAM-16-A), List $399 $269

A&T (RAM-16-A/A), List $459 . . . $309
32 K Kit (RAM-32), List $599 .... $499
32 K A&T (RAM-32/A), List $659 . . $549
CROMEMCO RAM Card w/bank select, A&T

16K (16KZ-W), List $595 $495

64K (64KZ-W), List $1795 $1485

MEASUREMENT SYSTEMS & CONTROLS
Guaranteed performance, incl. labor/parts 1 yr
64K Board with all 64K, A&T, ($795) . $659

with 48K, A&T, List $695 $589

with 32K, A&T, List $595 $509

PROBLEM SOLVERS — 1-year warranty
16K Static RAM Bd (to 4 MHz) A&T $319
MORROW SuperRAM. A&T
16K Static Board, 4 MHz, List $349 . $299
32 K Static Board, 4 MHz, List $699 . $629
VECTOR GRAPHIC, 8K Static, A&T . $189

48K Static Board, List $695 $589

SD ExpandoRAM w/o RAMS $139

32K Dynamic with 8K, Kit $189

32K Dynamic with 16K, Kit $237

32K Dynamic with 32K, Kit $329

ITHACA AUDIO 8K Static 250ns,A&T $175

FLOPPY DISK
CONTROLLER BOARDS

MORROW Disk Jockey 1 , A&T ($213) . $189
Disk Jockey 2D, A&T, List $479 . . . $429

SD Versafloppy, Kit, List $159 $139

DELTA Double-Density A&T ($385) . $345
CONDUCTOR, double-density A&T . . $269
ITHACA AUDIO, A&T, List $175 .. . $155
TARBELL Floppy Disk Interface, Kit . $169
MICROMATION Doubler, double-density
Controller Board, A&T, List $495 . . $419

INTERTUBE II, List $995 . . . ONLY $799
PERKIN-ELMER 550, List $997. . . . $799

with anti-glare screen, $1027 $819

HAZELTINE 1400, List $850 $699

1410, List $900 $749

1420 $849

1500, List $1225 $989

1500 Kit, List $1125 $799

1510, List $1395 $1089

1520, List $1650 $1389

ADDS R-20, List $995 $945

R-100, List $1325 $1295

LEAR SIEGLER ADM3A Kit $775

ADM3A Assembled $849

ADM31, List $1450 $1295

ADM42, List $1795 $1595

SOROC 120, List $995 $795

IQ140, List $1495 $1249

VT-100 — call for price!

EXIDY SORCERERS — all models -
at excellent prices!!

PRINTERS

ANADEX80-col dot matrix, $995 . . . $895
INTEGRAL DATA IP-125 w/1210 op. . $754
IP-225 W/1210& 1250 op.. $984 .. $889
IP-225 w/1210, 1250, 1241 (graphics)

options, List $1098 $949

IP-440 Paper Tiger, List $995 $895

w/graphics op. incl. buffer $1194 $1069

CENTRONICS779-1, List $1245. . . $ 949

779- 2 w/tractor, List $1350 1049

780- 2 w/tractor. List $1725 1295

701- 2 w/tractor, List $2205 1895

702- 2 w/tractor VFU, List $2480 .. 1995

703- 2 w/tractor VFU, List $2975 .. 2395

704- 2 w/tractor. List $2350 1995

730-1 parallel interface. List $995 . . . 895
730-3 RS232 interface. List $1045 . . 939
753-1 , List $3095 2785

T.l. 810 basic unit. List $1895 .... $1695
810 serial/parallel. List $1940 . . . $1735
DATA PRODUCTS M200-01 7, $3465 $3119
NEC Spinwriter 5510 RO/RS232 .. $2495
5520 KSR/RS232, List $3090 .... 2779
5530 RO/Centronics interf., $3275 . 2475
5503 12-bit Qu me interf., $2355 . . . 2119
5501 12-bit Diablo interf., $2355 . . 2119
for forms tractor on any above . ADD $190
TELETYPE 43 KSR/RS232, $1235 . $1087
DecWriter II (LA 36-DK), $1545 . . . $1490

IV (LA34), List $1450 $1195

LA 120, List $2375 $2169

VIDEO BOARDS

SD COMPUTER VDB-8024 Video
Display Bd, I/O mapped, kit, $319 . . $279

Assembled, List $469 $399

IMSAI VIO-C Video Interface Bd, memory

mapped. Kit, List $325 $285

Assembled, List $465 . $395

VECTOR GRAPHICS Flashwriter®

FW-64 memory mapped, A&T, $235 $199

FW-80U/LC 80-char, line, A&T, $320 $275
XITEX SCT-100K, Kit ... ONLY $154.95

SCT-100A Assembled $174.95

SSM VB1B Memory Mapped Video
Interface, 16x64, Kit, List $149 . . . $134
Assembled & Tested, List $199 ... . $179
SSM VB2 I/O Mapped Video Interface

Kit, List $159 $143

Assembled & Tested, List $224 .... $199
ITHACA AUDIO Memory Mapped
Video Board, 16x64, A&T, List $165 . $149

SHIPPING, HANDLING & INSURANCE: Add $2 for boards, $ 5 for Selectric converter, $15 for
Horizons and Cromemco systems. DEC and Centronics printers shipped freight collect. Contact
us for shipping information on other terminals and printers,
terminals & printers.

All prices subject to change and all offers subject to withdrawal without notice. Prices in this ad
are for prepaid orders. Slightly higher prices prevail for other-than-prepaid orders, i.e., C.O.D,
credit card, etc.

-WRITE FOR FREE CATALOG -

“ MiniMicroMart, Inc.

161 8 James St., Syracuse, NY 13203 (31 5) 4224467 TWX 71 0-541 -0431

Computer Products

The Exidy
SORCERER

Flexibilty is the key. The Sorcerer Computer gives you the flexibility of using ready-to-
run. pre-packaged programs or doing your own thing and personalizing the programs for
yourself Which ever you choose the Sorcerer is the personal computer that speaks your
language.

The Sorcerer also provides full graphics capacities Each character, formed by an 8 x 8
dot cell, can be programmed as a graphic symbol set High resolution (512 x 240
addressable points) gives a total of 122.880 locations for super animation and extremely
tight plotting curves The alphanumeric set gives 64 x 30 characters on the video screen
PART NUMBER: SYO-5016A

With 16K of memory $1150.00

Rockwell Aim-65: The Head-Start
in microcomputers

AKIM-1 compatible machine with
on-board printer and o reol key-
board!

*375.00 w/1 K RAM
*450 00 uj/ 4K RAM
4K assembler/editor in ROM: *80
8K BASIC in ROM: *100 00

Power Supply: *59.95

Cose of AIM-65 *49.95

Special Package Price: $599.00

AIM-65 (4K). Power SuddIv. Case, and 8K BASIC ROM

NOVATION a CAT acoustic modcm

Feotures Include: 300 Baud
• Rnsuuer/Originote. Bell 103, Comes

$ I 89.00

PROTO BOARD

Includes gold plated
fingers. S-100 size, holds
72-16 pin dips, accomo-
dates all 8 thru 40 pm dip
packages

Reg -Si 9 95 Special Price-
516 95 PART TSX-140B

SD SYSTEMS
SBC-100

An S-130 Single board com
outer Z-80 CPU w.lh 1024
byles Ol RAM 810 32K bytes
ot PROM Serial i O port

Kit $239.95

Assembled $369.95

SD SYSTEMS
Z-80 STARTER KIT

Based on the powerful Z80
CPU. this kit is an ideal
introduction to micropro-
cessors. It has an on-board
keyboard and display, plus

cassette tape interlace and
expansion provisions for
two S-100 connectors This
"Do-it-air Board will also
program the 2716 2K
EPROM

Kit $249 95

Assmbld and Tstd $399.95

TEXTOOLZIP DIP® II

PRICES

16 pm Zip Dip II
24 pm Zip Dip II
40 pm Zip Dip It

$5.50

$7.50

$10.25

LEEDEX MONITOR

• 12 Black and White

• 12MHZ Bandwidth

• Handsome Plastic Case

$ 139. 00

TRS -80- APPLE 'SORCERER -TRS-80'APPL

JADE MEMORY
EXPANSION KITS For
TRS— 80. Apple, & Exidy
41 16'»

Everything a person needs to
add 16K of memory. Chips
come neatly packaged with
easy to follow directions. In
minutes your machine is
ready for games and more
advanced software.

$82.00

HIGH QUALITY 13 INCH COLOR
MONITOR!— Specially matched for
use with the TI-99/4 console. Uses a
simple, sure hook-up.

UP TO 72K TOTAL MEMORY
CAPACTIY — 16K RAM, plus up to
26K ROM onboard, plus up to 30K
ROM in TI s Solid State Software
Command Modules.

16-COLOR GRAPHICS CAPABIL-
ITY- Easy to access high resolution
graphics have special features that
let you define your own characters,
create animated displays, charts,
graphs, etc.

MUSIC AND SOUND EFFECTS-
Provides outstanding audio
capability. Build three-note chords
and adjust frequency, duration and
volume quickly and simply. You can
build notes with short, straightfor-
ward commands. Five full octaves
from 110 Hz to beyond 40,000 Hz.
BUILT-IN EQUATION CALCULA-
TOR— Unique convenience feature
helps you find quick solutions to
everyday math problems, as well as
complex scientific calculations.

TSCflS INSTRUMENTS

TI-99/4

HOME

COMPUTER

FEATURES INCLUDE A COLOR MONITOR.

1 6K RAM MEMORV, BASIC BUILT INTO THE
CONSOLE. AND TUUO COMPREHENSIVE MAN-
UALS EASY FOR THE BEGINNER - CHALLENG-
ING FOR THE EXPERT

Programs are sealed securely in SOLID STATE
SOFTWARE COMMAND MODULES. These ROM
packs actually add memory to the TI-99/4 so that the
console s memory can be utilized for user input.

The software applications are presently broken down
into four areas: 1) Home Management/Personal

Finance. 2) Education. 3) Entertainment. 4) BASIC.

SVO-8994A $11 50.00

JADE SERIAL/PARALLEL I/O BOARD

Features Include: S-100 Compatible ■ Two serial I/O Ports using
software-programmable UARTS ■ One general purpose latched parallel
I/O Port ideal for printer interface or control ■ Switch selectable ■ On
board ‘Kansas City" standard cassette interface useable upto 1200 Baud,
allowing storage of up to 180,000 bytes on a 30 minute audio cassette.
Assembled and Tested Kit

IOI-1040A S179.95 IOI-1040K, $124.95

Bare Board with Manual |Qj-1Q40B, $30.00

SVM-l

$245

Port Number:CPK-5002A
6502- BASED SINGLE BOARD COMPUTER WITH
KEYBOARD/DISPLAY, KIM-1 HARDWARE
COMPATIBLE. COMPLETE DOCUMENTATION.

SVM-l CASE. ENX-000005 ^9 95

THEBIGZ

THE NEW Z-80

CPU BOARD FROM JADE

Features Include: ■ S-100 Compatible, available in 2MHz or4MHz
versions ■ On-board 2708. 2716. 2516. or 2532 EPROM can be
addressed on any IK. 2K. or 4K boundary, with power-on jump to
EPROM ■ On-board EPROM may be used in SHADOW mode,
allowing full 64K RAM to be used. ■ Automatic M WRITE generation
it front panel is not used. ■ On-board USART for synchronous or
asynchronous RS232 operation (on-board baud rate generator). ■
Reverse-channel capability on USART allows use with buffered
peripherals or devices with not-ready signal.

2MH: BARE BOARD 4 WlHz-

n CPU-30200B.... $40.00

Kit: CPU-30200K. 2 lbs $149 95 Kit: CPU-30201 K. 2 lbs $159.95

Assembled and Tested. Assembled and Tested

CPU-30200A. 2 lbs $199.95 - CPU-30201 A. 2 lbs S209.95

GRI KEYBOARDS

Features Include: Full 128 character ASCII ■
Trl-Mode Mos encoding ■ MOS/DTL/TTL
compatible output ■ Two-key rollover ■ Level
and pulse strobe ■ Shift and alpha lock ■
Selectable parity ■ Positive or Negative Logic
■ All new OEM grade components ■ Gold
contact, low bounce keyswithces ■ Rugged G-
10 printed circuit board ■ Custom 2 shot
molded keycaps ■ Low power consumption ■
Optional numeric pad available ■ Custom
enclosures available.

Model 756A

Assembled- KBA-30756A $79.95

Model 753K (53 Key, Teletype Keyboard with
lower case)

Kit- KBA-30753K $65.95

DB25-CONNECTORS

DB25P- CND1251 $2.25

DB25S- CND1252 $3.25

DB25C- CND1253 (Cover) $1.50

RS232 Special: DB25P, DB25S, plus Hood
only $6.50 (Part Number: CND-1250)

kcts i»

ZERO ^' Um,QtIU:

INSERTION FORCE

MICROPROCESSORS

F80

$16.95

Z80 (2MHz)

$10.95

Z80A (4MHz)

$14.95

CDP1802CD

$19 95

6502

$11.95

6800

$9.75

6802

$14.00

8008 1

$15.95

8035

$24.00

8035-8

$24.00

8080-A

$10.00

8085

$23.00

TMS9900TL

$49 95

8080A SUPPORT DEVICES

8212

S290

8214

S4 65

8216

$2.75*

8224 (2MHz)

$4.30

8226

$2.75

8228

$6.40

8238

S6.40

8243

S8.00

8251

$7.50

8253

$20.00

8255

$6.40

8257

$18.00

8259

$18.00

8275

$51.20

8279

$17.70

USRT

S2350

$10.95

UARTS

AY5-1013A

$5.25

AY5-1014A

$8.25

TR1602B

$5.25

TMS6011

$5.95

6800 PRODUCT

682 IP

$5.25

6828P

$9.50

6834P

$16.95

6850P

$4.80

6852P

$5.25

$9.25

$ 12.00

$7.30

$2.50

6860P
6862P
6875L
6880P

CHARACTER GENERATORS
2513 Upper (1-12 5) $6.75

2513 Lower (1-12 -5) $6.75

2513 Upper (5 volt) $9.75

2513 Lower (5 volt) $10.95

PROMS

1702 A $5.00

2708 $9.95

2716 $49.95

2716 (5v) $49 95

2758 (5v) $30.00

DYNAMIC RAMS

4115

$5.00

416D/41 16 (200ns)

$12.50

2104/4096

$4.00

2107B-4

$3.95

TMS4027/4096

$4.00

STATIC RAMS

1—15

16—100

2114 (450ns)

$8.00

$6.95

2114 (300ns)
TMS4044/

$9.00

$8.00

MM5257(450ns)

TMS4044/

$8.00

$7.50

MM5257(300ns)

$9.95

$8.75

21L02 (450ns)

$1.50

$1.20

21L02 (250ns)

$1.75

$1.50

4200A (200ns)

$9.95

$8.50

41 0D (200ns)

$8.25

$7.00

210 Microcomputing, October 1979

PRICES GOOD IN TH€ UNITED STATES AND CANADA

n j APP HDHP D Q TOl I CDCC- 800/421-5809 Continental U.S.

Y L AO t On Ut no I ULL rntt* 800 / 262-1710 Inside California

When visiting the Los Angeles area, visit JAD€'s retail store at 1 3340 S. Hacuthorne Blvd. in the city of Hamthorne

INTEGRAL DATA SYSTEMS MODEL 440 PRINTER

THE PAPER TIGER

i Up to 198 cps $995.00

I 1.75" to 9.5" Adjustable Tractor feed
I Parallel and Serial Interface
I 96 Character ASCII Set
l 1 32 columns- 6 or 8 lines/inch
l Cight softujare selectable Character sizes
1110, 300, 600, 1200 Baud Rate

FOR THE GRAPHIC OPTION WITH 2K. ADD SI 99 00

1 r ■ \ /

■y 1

Su,

Part Number: PRM-33440

MEM-2

16 K Static RAM Board

Kit (450ns)

S250 00

SWD-103

$1.18

SWD-107

Kit- (250n$)

S28S 00

SWD-104

$1.20

SWD-108

Assembled (450ns)

$325 00

SWD-105

$1.24

SWD-109

Assembled (250ns)

$350 00

SWD-106

SI. 28

SWD-110

DYNAMIC RAM BOARDS

EXPANDABLE TO 64K

32K VERSION • KITS

JSes 4115 (8Kx 1, 250ns) Oynan
RAM's, can t>e expanded m
ncremenls up to 32K

8K $159 95
16K $199.95

24K $249 95
32K $299 95

64 K VERSION • KITS

ses 4116 (16Kx 1. ?OOns) Dynamic
RAM's, can pe expanded in 16K
nc remen ts up to 64 K

16K $249 95
32K S369 95

48K $469 95
64 K $569 95

DIP SWITCHES

Part No. positions 1-9

7 $1 .30

8 $1 34

9 $1.36

10 SI. 38

STATIC RAM
BOARDS

JADE 8K

Kits: 450ns $125.95

250ns $149.75

Assembled & Tested:

450ns $139.75

250ns $169.75

Bare Board: $ 25.00

32 K Static

Assembled & Tested:

250ns
450ns
250ns Kit

$795.00

$725.00

$575.00

L.S. Engineering
EPROM Eraser

Features Include: Erases
up to 48 I.C.3 at a time ■
Uses popular (and readily
available 12* shortwave
UV bulbs) ■ Handsome
smoke-plastic case ■
Includes bulb ■

Just plug it in and you’re
ready to go!

XME-3200,

$39.95

POWER

SUPPLIES

SD 249A For a Single 5 1 4 Dish
Irive By Power One or Alpha Power

+5V at.7A, +12V at 1.1 A $52.00

PSD 205A For Single 8 Disk Drive
By Power One 5V at 1A 5V at 5A
24V at 1 5 A S89 95

PSD 206A For Two 8 Disk Drives
By Power One or Alpha Power 5V
at 2 5 A SV al 5A 24V at

S125 00

Rockwell Aim 65 Power Supply
PSX 030A S59 95

KIM 1 or SYM 1 Power Supply
PSX 020A SS995

CABLES

MINI DISK CABLE KIT To conned
two 5 1'4 drives to disk controller
board Contains assembled and testec
5 long signal cable wiih 34 pin edge
connectors Also includes cables and
connector for D C power supply
WCA-3431K $34 95

8 DISK CABLE KIT To connect two 8
disk drives to edge-type controller
(eg Versaflcppy Double-D)
Contains assembled and tested signal
cable with connectors plus cable and
connectors for both A C and D C.
power

WCA-5031K

$38 45

8 DISK CABLE KIT Same as WCA
5031K except controller end of signal
cable uses Header type connector,
e g for Tarbell Controller
WCA 5032K $38 95

SIGNAL CABLE ONLY For one 5 1/4
drive to edge type controller connector
(e g TRS-80 to Vista Disk Drive)

WCA 3421A S24.95

Same as Above, except lor two 5 1/4
drives WCA-3431A $29 95

JAD€

FLOPPV DISK
SPECIAL

INCLUDES: ■ Tujo Siemens/GSI 8"
Floppy Disk Drives ■ Power Supply ■
Jade Double Density Board (Kit) ■
CP/M’" Operating System with Basic
€ (CP/M is a registered trademark of
Digital Research) ■ Package of 10
Blank 8" Diskettes (Double Density)
■ Interface Cobles.

IF purchased seperately this
package would cost: SI 544.95.

JADE SPECIAL
$1225.00

JADt
ISO-BUS
MOTHERBOARDS
Comes in either 6, 12. or
18 slot sizes. These
boards with a special
ground plane assure a
silent operation
JADE 6 Slot
Kit $4995

Assembled $59.95

Bare Board $24 95

JADE 12 Slot
Kit

Assembled
Bare Board

JADE 18 Slot
Kit

Assembled
Bare Board

$89 95
$99 95
$3995

$129.95
$149 95
$59.95

THE PIGGY MAINFRAME

This sleak new mainframe is neatly trimmed to hold six S-100
boards, three mini-floppy drives, and is available in five colors. Power
requirements: 115/220 VAC, 50/60 HZ. Weight: 27 lbs. (with drives).
Dimensions: 21 .375 Wide X 8.4' High X 15.875" Deep. Power Supply:
8 volts at 18 Amps unregulated. 16 volts at 3 amps unregulated, - 16
volts at 3 amps unregulated. • 5 volts at 3 amps regulated. 1C volts at
3 amps regulated.

THE PIGGY IS HERE!

THE PIGGY (Without Drives)

PART NUMBER ENS-106320

$475.00

SPECIAL

5’A" Diskettes
$29.95/Box of TEN

SPECIFY SOFT, 10, or 16 SECTOFI

8" SINGLE SIDE, SINGLE DENSITY
154.95/Box of TEN

THE JRDE "DOUBLE-D”
INTELLIGENT
DISK CONTROLLER

• ki \i> wkiii i\ siN(ii i ok norm i

1)1 NNI I V

■ X" or 5'j" DR I VI S

■ CT M COM PA I I B II IN II I HI R
DL NSI I Y

■ ONBOARD ZX0 CPI ALLOWS
I NIVL RSAI. SYS I I M COM PA I IBI I I I Y

■ PROGR AM MI D DA I A I RANSLI R - NO
DMA

■ CON I ROI.S IP I O X I)R I VPS

■ SOM WAR! SI ILC I ABM 1)1 NSI I Y

Our new controller utilizes the IBM standard
formats lor proven reliability Data recovery is
enehaeed through use ol a phase-loeked-loop
data sc pe rat ion circuit and write
precompensation. Single and double density
diskettes can he mixed in the same svstem.
Assembled and tested
I()D-I2(K)A, 2 Ihs
Kit

IOD-I200K. 2 Ihs
Bare Board w Manual
IOD-I200B. 2 Ihs
Manual

IOD-I200M. I lb

$299.95
S249.95
. . S55.00

. . $ 10.00

VB-1B VIDEO INTERFACE

S-100 Compatible Serial Inter
face with Sockets Included.

Kit $117.95

Assembled 6. Tested $159.95
Bare Board w/manuai $ 35.00

FLOPPY DISK INTERFACE

JADE FLOPPY DISK (Tarbell
board)

JADE KIT $190.00

Assembled & Tested $260.00

S.O. Computer Products

VERSA-FLOPPY

*•* $159 95

Assembled 8. Tested S239 00

DISK DRIVES

MPI B51 5 1/4 " MSM — 155100 $295.00
Single or double density, up to 40
tracks, track to track access time
only 5ms.

MPI B52 5 1/4’ MSM 155200 $450.00

Double head version of MPI B51
Shugart SA400 5 1/4” . $325.00

Single Density, 35 Track
Siemens FDD100-8 8 $495.00

Shugart 801 R replacement. Single or
double density, runs cooler and
quieter.

Siemens FDD200-8 8” $575.00

Double head version of FDD100-8
capable of double density, double
sided storage.

Shugart 801 R 8 " $575.00

Hard or soft sectored, 400K BYTE
drive.

vista V80

mini dish

SYSTEM

FOR TRS—80
$ 395.00

*>J6

Computer Products

4901 W. ROSECRANS AVE., HAWTHORNE. CALIFORNIA, 90250

(213) 679-3313

ORDER TOLL FREE

800-262-1710

INSIDE CALIFORNIA

800-421-5809

CONTINENTAL U.S.

WRITE FOR OUR FREE CATALOG

Cash, checks, money orders, and credit cards accepted.
Minimum order $10.00. California residents add 6°/o sales tax.
Minimum shipping and handling charge: $2.50. Discounts
available at OEM quantities.

PRICES SUBJECT TO CHANGE WITHOUT PRIOR NOTICE
For €xport information send for o JRDE INTERNATIONAL CATALOG

PART NUMBER. MSM-358000
Includes disk drive, power supply,
regulator board, and compact case.
The V-80 offers 23 # o more storage
capacity Simply take it out of the box.
plug in the cable, and it's ready to run
Requires 16K Level II. expansion
interface

Interlace Cable . . $24.95

PART NUMBER: WCA-3421A

t* 0 Reader Service— see page 227

Microcomputing, October 1979 211

WAMECO

»^W22

THE COMPLETE PC BOARD HOUSE
EVERYTHING FOR THE S-100 BUSS

NEW! POWER SUPPLY AND TERMINATOR BOARD. PROVIDES UP TO
12 REGULATORS TO DRIVE ALL THOSE PERIPHERALS FROM THE
COMPUTERS POWER SUPPLIES. TERMINATES THE MOTHER BOARD.

SPECIAL OCT. PRICE $28.95. AFTER OCT. 30 $30.95

AT YOUR DEALER NOW!

c FUTURE PRODUCTS: 80 CHARACTER VIDEO BOARD,

10 BOARD WITH CASSETTE INTERFACE.

DEALER INQUIRIES INVITED, UNIVERSITY DISCOUNTS AVAILABLE

AT YOUR LOCAL DEALER

wmc inc

WAMECO INC. Ill GLENN WAY #8, BELMONT, CA 94002

(415) 592-6141

i§

wmmm California computer systems

16K RAM BOARD Fully buffered addressable in 4K
blocks. IEEE standard for bank addressing 2114 s
PCBD $26.95

Kit 450 NSEC $259.95

PT-1 PROTO BOARD Over 2,600 holes 4" regu-
lators. All S-100 buss functions labeled, gold fingers.

PCBD $25.95

PT-2 PROTO BOARD. Similar to PT-1 except set-
up to handle solder tail sockets.

PCBD $25.95

==tV

FORMERLY CYBERCOM SOLID STATE MUSIC.

PB-1 2708 & 2716 Programming Board with provisions
for 4K or 8K EPROM. No external supplies require

textool sockets Kit $124.95

CB-1 8080 Processor Board. 2K of PROM 256 BYTE
RAM power on/rest Vector Jump Parallel port with
status Kit . $119.00 PCBD $30.95

MB-6B Basic 8KX8 ram uses 2102 type rams, S-100

buss Kit 450 NSEC $139.95 PCBD $26.95

MB-7 16KX8, Static RAM uses u p41 ° Protection,
fully buffered Kit $299.95

MB-8A 2708 EROM Board. S-100 8K8X or 16Kx8
kit without PROMS $75.00 PCBD $28.95

MB-9 4KX8 RAM/PROM Board uses 2112 RAMS or
82S129 PROM kit without RAMS or PROMS $72.00
IO-2 S-100 8 bit parallel / 10 port, Vj of boards is for

kludging. Kit $46.00 PCBD $26.95

IO-4 Two serial I/O ports with full handshaking
20/60 ma current loop: Two parallel I/O ports.

Kit $130.00 PCBD $26.95

VB-1B 64 x 16 video board, upper lower case Greek,
composite and parallel video with software, S-100.

Kit $125.00 PCBD $26.95

Altair Compatible Mother Board, llxllVfrxVk".

Board only $39.95. With 15 connectors $94.95

Extended Board full size. Board only $ 9.49

With connector $13.45

SP-1 Synthesizer Board S-100

PCBD $42 95 KIT $135.95

fYim Cjine. WAMECO INC.

FDC-1 FLOPPY CONTROLLER BOARD will drive
shugart, pertek, remic 5" & 8" drives up to 8 drives,
on board PROM with power boot up, will operate
with CPM (not included).

PCBD $42.95

FPB-1 Front Panel. IMSAI size, hex displays Byte,
or instruction single step.

PCBD $47.50

MEM-1 8KX8 fully buffered, S-100, uses 2102 type

rams. PCBD $25.95

QM-12 MOTHER BOARD, 13 slot, terminated, S-100

board only $34.95

CPU-1 8080A Processor board S-100 with 8 level

vector interrupt PCBD $26.95

RTC-1 Realtime clock board. Two independent in-
terrupts. Software programmable. PCBD $23.95
EPM-1 1702A 4K Eprom card PCBD $25.95

EPM-2 2708/2716 16K/32K

EPROM CARD PCBD $25.95

QM-9 MOTHER BOARD, Short Version of QM-12.

9 Slots PCBD $30.95

MEM-2 16K x 8 Fully Buffered

2114 Board PCBD $26.95

8080A $9.95

8212 2.49

8214 4.49

8224 3.49

2708 9.49

5101-IP 6.90

5101-8P $ 8.40

2114 (450 NS) low pwr 7.25
2114 (250 NS) low pwr 7.99

2102A-2L 1.50

2102A-4L 120

4116 8/89.95

P. O. Box 424 • San Carlos, California 94070

Please send for 1C, Xistor
and Computer parts list »^M39

OCT. SPECIAL SALE
ON PREPAID ORDERS

(Charge cards not included on this offer)

WAMECO PWR SUPPLY AND TERMINA-

TOR BOARD

12 Regulators for driving external equip-
ment $24.95

8KX8RAM. Fully buffered 450 NSEC. 2.5
amp typical assembled parts may be un-
marked or house numbered . . . $99.99
MIKOS PARTS ASSORTMENT
WITH WAMECO AND CYBERCOM PCBDS

MEM-2 with MIKOS -7 16K ram

with L2114 450 NSEC $249 95

MEM-2 with MIKOS -13 16K ram

with L2114 250 NSEC $279 95

MEM-1 with MIKOS #1 450 NSEC 8K

RAM S1 19 95

CPU-1 with MIKOS #2 8080A CPU $94.95

MEM-1 with MIKOS #3 250 NSEC 8K

RAM $144 95

QM-12 with MIKOS #4 13 slot mother
board $89.95

RTC-1 with MIKOS #5 real time clock $54.95

EMP-1 with MIKOS #10 4K 1702 less

EPROMS $49 95

EPM-2 with MIKOS #11 16-32K EPROMS

less EPROMS $5995

QM-9 with MIKOS #12 9 slot mother

board $79.95

FPB-1 with MIKOS =14 all parts

for front panel $134.95

MIKOS PARTS ASSORTMENTS ARE ALL FACTORY PRIME
PARTS KITS INCLUDE ALL PARTS LISTED AS REQUIRED
FOR THE COMPLETE KIT LESS PARTS LISTED ALL SOCKETS
INCLUDED.

VISA or MASTERCHARGE Send account number, interbank
number expiration date and sign your order. Approx postage
will be added Check or money order will be sent post paid in
U.S. If you are not a regular customer, please use charge,
cashier's check or postal money order. Otherwise there will
be a two-week delay for checks to clear Calif, residents add
6% tax Money back 30 day guarantee. We cannot accept re-
turned IC’S that have been soldered to. Prices subject to
change without notice. $10 minimum order. $1.50 service charge
on orders less than $10.00.

212 Microcomputing, October 1979

ELECTRONIC COMPONENTS
TEST EQUIPMENT
CONNECTORS-WIRE

WALLEN

ELECTRONICS CO. INC. Tel: (617) 588-6440-6441
108 SAWTELL AVE., BROCKTON, MA. 02402

REGULATED

COMPUTER

POWER SUPPLIES

Ideal for micro and mini computers. These units have been removed from equip-
ment, checked out and guaranteed. 5 volts @ 8 amps + 12 volts. 2 amps +

6 volts @ 75 MA. Power supply has a 3-wire line cord and fused. Dimensions:
10%"x5y4"x4%". Shipping weight: 16 lbs.

37.50

2 FOR 70.00

WIRE WRAP BOARDS

These boards are pre-wired and removed from equipment. Easy to unwrap
for setting up your own board, contains mostly 14-pin 1C sockets with
individual pin connections. Each board has VCC and ground planes.

Smaller board measures 6%"x6'
Larger board measures 1 3%"x6"

and has 40 to 50 sockets,
and has 75 to 100 sockets.

Reduced prices

$7.50 ea.2/$14.00

P» 3r$17.50 lu. gj$33330 $12.50 ea.2/$23.00

DIABLO SYSTEM DISC DRIVE

SERIES 40 MODEL 43 100 tracks per inch, total
capacity of 50 megabits, w/Model 429 power supply,
sector counter, 24 sectors, 1 fixed disc, 1 removable
disc, average access time 38 ms, PPM: 2400, dimen-
sions: 10 5/16" high, fits in standard rack, equipped
with full extension slides, excellent used condition.
Shipped freight collect.

$2495

FM SIGNAL GENERATOR

MEASUREMENTS MODEL 560 FM
Frequency 25 mhz to 80 mhz and 130-175 mhz. Di-
mensions: 10"x10"x16", weight: 16 lbs. Shipped
freight collect. Used. Checked out and operating.

$289

TRANSFORMERS isolation step-down type

Primary: 230/1 15V, 50/60 CPS, Secondary: VA output 250V.

$13.95

EACH

7444

I.C

74H72J

7450

74H72N

7453

74H73N

7460

74H76N

7470

74H87N

1.30

7482

.50

74H101J

.65

7490 ....

74H103J ....

7491 ....

74H108J ....

74104 ....

74H50 ....

74111 ....

74H40

74121 ...

74H51

74122 ...

74H21

74142 ...

74H30

74145 ...

74S09

74156 ...

74S134

74180 ..

74S135

74198 ...

1.45

75150

74249 ...

75154

1.25

74265 ..

LM101H

74H05N .

LM318H ....

1.25

74H15N ..

NE531T ....

74H22J ..

NE565A ....

74H60N .

LM556CN ...

74H61J ..

74H61N ...

74H71N ..

CA324G

RC741DP

RC747DP

MEMORY

PHONES

By FORD INDUSTRIES, INC.

These units have complete
installation and operating
instructions w/6-foot cord.
Colors: beige, white, green.
Used, operating condition.

$89

TRENDLINE

PHONES

Mfd. by I.T.T.

Rotary dial. Colors: white,
black, red, green. Packaged,
has 6-foot cord and instal-
lation instructions. Used,
operating condition.

34.50

HEWLETT-PACKARD
Model 175A

OSCILLOSCOPES

These scopes have a 50 Mhz band-
width and have 2 plug-ins, a 1781B De-
lay generator and a model 1755A Dual
trace vertical amplifier. Dimensions:
13"x17"x25", weight 71 lbs. shipped
freight collect.
5" scope. Used.
Checked out
and operating.

$339

ROT RON
WHISPER FANS

Unused, Model Rotron
MU 3A1, 230V, AC, 14 qp

watts, 50/60 hz, guar-
anteed, 4 1 / 2 "x4% , 'x1!4".

CRYSTAL

OSCILLATORS

Vectron type CO-23 IT
crystal freq. 4.9152, MHZ
w/tuning option for ac-
curacy of .0001%. 1%"x

1%"x%".R.F.E. 13.95

INCANDESCENT
READOUT ASSEMBLY

Readouts assembled of the
710 series modules. Character
high w/lamps. Type No.

344. By Dialco.

1.50

EACH

I.C. SOCKETS

14-PIN Wire Wrap 30

14-PIN Low Profile 15

28-PIN Low Profile 35

40-PIN Low Profile 50

Minimum order $25.00. Items offered subject to prior sale. FOB, Brockton, Mass. Money order or check w/order. Shipping and
handling add 5%. Shipments by parcel post or UPS. No CODs. Mass, residents add 5% sales tax.

v* Reader Service— see page 227

Microcomputing, October 1979 213

TRS-80

DRIVE

$ 395 00

Shugart SA400, housed in an attractive met&l case,
complete with power supply and termination net-
work. All you need to do is connect the drives to your
expansion interface.

1410 $835®® * Separate integral 12-key Numeric Pad

• All 128 ASCII Codes
64 Displayable Characters
24x80 Screen Configuration
High Resolution using a 5x7 Dot Matrix
TTY-Style Keyboard Layout
Cursor Addressing and Sensing
EIA Interface

Eight Selectable Transmission Rates up
to 9600 Baud
Microprocessor Based

• Remote Commands
L* Attractive Styling for Contemporary En-

vironments

Hazeltine 1400

same as 1410 less numeric pad

S73500

Hazettine14l0

Reg. $ : t225 S 1 098 00 • All 128 ASCII Codes

• 94 Displayable Characters Including
Lower Case

» 24x80 Screen Configuration

> High-Resolution Characters Using a
7x10 Dot Matrix

• ANSI Standard Keyboard Layout in-
cluding Numeric Pad

• Cursor Addressing and Sensing

• Dual Intensity

• EIA and 20MA Interface

> Nine Selectable Transmission Rates Up
to 19.2 KB

• Auxiliary EIA Output

• Remote Editing Command?

• Standard or Reverse Video
Microprocessor Based

.THE FEATURES OF THE
“1500” PLUS . . .

• Cursor Control Keys

• Protected/Unprotected Data

• Transmit Page, Line or Batches of Infor-
mation

• Function Keys— up to 127

• Tab/Back Tab/Auto Tab

• Format Mode with Insert and Delete
Line Keys

31 Remote Commands including "Ter-
.minal Status"

1510 Reg.jPteaff,

S 11 75

THE FEATURES OF THE
“1510” PLUS . . .

Separate Microprocessor-Controlled Printer In-
terface which allows:

• Interfacing of both serial and parallel printers

• Printer speed independent of communications
baud rate

• Printer control codes to be sent by the CPU
and received by the printer without restriction
or alteration of the terminal (especially useful
for wide carriage applications)

• Information to be transmitted directly to eitherl
the printer or the terminal, or to both

i» Operating Modes/Remote Commands;

I Remote/Local Print; Printer On-Line
with/without Display; Printer Off-Line

1520
Reg. $T65CT
M495 00

PRICE POES NOT INCLUDE SHIPPING

• Use with TRS-80

• Parallel interface

• Continuous variable printing density
80-132 characters per line

• 5x7 dot matrix

• Prints on plain paper, sheets,
rolls, fan fold

• Form thickness control

• Horizontal and vertical
form positioning

779-1 pinch roll
friction feed
Reg. $1250 $950 00
779-2 tractor feet
Reg. $1400 $1050 00

I Call tor Discount Prices on Other Centronics Printers -

CENTRONICS 779 PRINTERS

1c sale Probes 1c with purchase of scope

• 30-Megahertz bandwidth • Accuracy 3% full scale. • Internal, line or external trigger. • Bat-
teries and charger/transformer unit included • Graticule: 4x5 divisions, each division 0.25” •
Time base: 1 micro sec. to 0.5 sec/div 21 settings • Verticle Gain: 0.01 to 50 Volts/div. 12 set-
tings • Size 2.9"H x 6.4”W x 8.5”D. 3.5 lbs. • TEST MOST DIGITAL LOGIC CIRCUITS IN-
CLUDING MICROPROCESSORS •.

41-141 Deluxe lOtol probe with 4 interchangeable tips $27.00

41-37 Deluxe lOtol/ltol probe with 4 interchangeable tips $38.50

41 -180 leather carrying case $45.00

MS-1 5 Single trace 15 MHz $318.00

MS-215 Dual trace 15 MHz $435.00

3M Scotch® Brand
DISKETTES

Part #

Sides/

Sectoring

Price

Density

8”

Soft-IBM

Box of 10

740-OP

1/single

$39.95

740/2-0 P

2/single

Soft-IBM

$75.00

740-32 P

1/single

32-Shugart 801

$39.95

740/2-32P

2/single

32-Shugart 801

$75.00

741-0

1/double

Soft-Shugart Dbl

c»

$59.00

744-0 K

1/single

Soft-Shugart SA400
(TRS-80)

$51.00*

744-1 OK

1/single

Soft/10 SA400

744-1 6K

1/single

Soft/16 Micropolis

$51.00*

•Price includes Kas
“DON’T SETTLE FOR

■ette/10 Storage Box a $5.00 Value
ANYTHING LESS THAN SCOTCH "

ACOUSTIC MODEM

NOVATION CAT

• 0-300 Baud

• Bell 103

• Answer, Originate

Reg. $198.00

Sale $189.00

SALE

REG.J55MIC,

100 MHz 8- Digit Co unter

• 200 Hz-100 MHz Range

• 6” LED Display

• Crystal-controlled timebase

• Fully Automatic

• Portable - completely
self contained

• Size - 1.75" x 7.38” x 5.63"

• Four power sources, i.e. batteries.

110 or 220V with charger 12V with
auto lighter adapter and external
7.2-1 0V power supply.

£t3*05"Sale $120.00

ACCESSORIES FOR MAX 100:

Mobile Charter Eliminator use power
|from car battery Model 100-CLA $3.95.

Charger/Eliminator use 110 VAC
Model 100 - CAI $9.95

^ PRIORITY ONE ELECTRONICS * -

16723B Roscoe Blvd. Sepulveda, CA 91343

Terms: Visa, MC, BAC, Check, Money Order, C.O.D. U.S. Funds Only. CA residents add 6% sales tax.
Minimum order $10.00. Prepaid U.S. orders less than $75.00 include 5% shipping and handling,
minimum $2.50. Excess refunded. Just in case . . please include your phone no. ^P2l
Prices subject to change without notice.

We will do our best to maintain prices thru Sept. 1979. OEM and Institutional

phone orders welcome (213) 894-8171, (800) 423-5633 inquiries invited.

E 1-800-423-5633

LOGIC MONITOR 1

Trace signals through all types of digital circuits. Unit
clips over any DIP 1C up to 16 pins. Each of its 16 contacts
connects to a single-bit level detector that drives a high-
intensity, numbered LED readout activated when the ap-
plied voltage exceeds a fixed 2 V threshold. Logic “I”
turns LED on; logic “0” keeps LED off. A power-seeking
gate network automatically locates supply leads and
feeds them to the LM-I’s internal circuitry. Saves minutes,
even hours in design, troubleshooting, debugging of
equipment. Voltage Threshold: 2 V ± 0.2 V. Input Im-
pedance: 100,000 ohms. Input Voltage Range: 4-15 V max.
across any two or more inputs. Current Drain: 200 mA at 10
V. Size: 4” I. x 2” w. x 1.75” d. when open. Weight: 3 ozs.
CSC Model LM-1 Logic Monitor— Complete.

Sale Price $54.95

our new retail location! Visit our new retail location!

Visit our new retail location! Visit our new retail location!

• Extensive documentation clear-
ly written

• Complete Kit includes all
Sockets for 64K

• Memory access time: 375ns,
Cycle time: 500ns.

• No wait states required.

• 16K boundries and Protection
via Dip Switches

• Designed to work with Z-80,
8080, 8085 CPU’s.

EXPAN DO 64 KIT (4116)

16K $249

32K $324

48K $399

64K $474

SD EXPAN DORAM

TUtunatc S-?00

The EXPANDORAM is available
in versions from 16K up to 64K, so
for a minimum investment you
can have a memory system that
will grow with your needs. This is
a dynamic memory with the in-
visable on-board refresh, and IT
WORKS!

• Interfaces with Altair, IMSAI, SOL-8,
Cromenco, SBC-100, and others.

• Bank Selectable

• Phantom

• Power 8VDC, ± 16VDC, 5 Watts

• Lowest Cost Per Bit

• Uses Popular 4116 RAMS

• PC Board is doubled solder masked and
has silk-screen parts layout.

isc DRIVES

DISC CONTROLLER

DUAL SHUGAR
DISC DRIVES.

SD “VERSAFLOPPY” Kit

The Versatile Floppy Disk Only S 159°°

Controller

New from Lobo Drives, a dual Cabinet complete with*power supply/
and Shugart 801 R disc drives.

• Cabinet accepts 2 801 R drives mounted side by side horizontally.

• Power Supply for 2 drives

• Ad-on drives available

• Assembled, tested and guaranteed by Lobo Drives.

• Single or double density • Hard or soft sector • Write Protect

l* Capacity: Unformatted single density 3.2 megabits
Mr double density 6.4 megabits

IBM format, 2 megabits

• 500 KBS transfer, 77 tracks.

• Shugart 800 Series Compatible
LOBO 801 R-1 Pcs. Dual Cabinet with 1 drive . ,

LOBO 801 R-2 Pcs. Dual Cabinet with 2 drives
SHUGART 801 R Ad-on disc drive

SHUGART SA 400 5V*”

110 KB, 35 tracks,
SHUGART SA 400 $295.00
SHUGART SA 400

with attractive metal case with
cutouts lor Data Cable switch,
fuse and power cord.

LOBO SA400-C $325.00
SHUGART SA400

with Cabinet and Power Supply
Assembled, tested & guaranteed

lobo sa4oo-psc $395.00
SHUGART 801 R 8”

6.4 megabits, single or double
density, hard or soft sector, write
protect, and more
SHUGART 801 R $449.00
Siemens FDD 200-8 8"
double-sided double density

FEATURES: IBM 3740 Soft Sectored Compati-
ble. S-100 BUS Compatible for Z-80 or 8080. Con-
trols up to 4 Drives (single or double sided).
Directly controls the following drives:

1. Shugart SA400/450 Mini Floppy

2. Shugart SA800/850 Standard Floppy.

3. PERSCI 70 and 277

4. MFE 700/750.

5. CDC 9404/9406.

6. GSI/Siemans FDD120-8.

34 Pin Connector for Mini Floppy. 50 Pin Con-
nector for Standard Floppy. Operates with
modified CP/M operating system and C-Basic
Comptler. The new “Versafloppy" from S.D.
Computer Products provides complete control
for many of the available Floppy Disk Drives,
Both Mini and Full Size. FD1771B-1 Single Den-
sity Controller Chip. Listings for Control Soft-
ware are included in price. c . /\/\on

kCPM for SD Versafloppy *1 00

. $599.00
$1025.00
. $449.00

CONTINENTAL SPECIALTIES CORPORATION

Logic Probes and
Digital Pulsers

LOGIC PROBES

CSC logic probes are the ultimate tool for breadboard design and testing
These hand held units provide an instant overview of circuit conditions
Simple to use; just clip power leads to circuit's power supply, set logic
family switch to TTL/DTL or CMOS/HTL. Touch probe to test node. Trace
logic levels and pulses through digital circuits. Even stretch and latch for
easy pulse detection. Instant recognition of high, low or invalid levels, open
circuits and nodes. Simple, dual-level detector LEDs tell it quickly, correct-
ly. HI (Logic “1”); LO (Logic "0”). Also incorporates blinking pulse detector
e.g., HI and LO LEDs blink on or off. tracking “1" or “0" states at square
wave frequencies up to 1.5 MHz. Pulse LED blinks on for Vi second during
pulse transition. Choice of three models to meet individual requirements;
budget, project and speed of logic circuits.

MODEL LP-1

Hand-held logic probe provides instant reading of logic levels for TTL, DTL,
HTLor CMOS. Input Impedance: 100,000 ohms. Minimum Detectable Pulse:
50 ns. Maximum Input Signal (Frequency): 10 MHz Pulse Detector (LED):
High speed train or single event. Pulse Memory: Pulse or level transition
detected and stored. ~ —

XSC Model LP-1 Logic Probe-Net Each $42.70

DIGITAL PULSER

The ultimate in speed and ease of operation. Simply connect clip leads to
positive and negative power, then touch DP-1's probe to a circuit node:
automatic polarity sensor detects circuit's high or low condition. Depress
the pushbutton and trigger an opposite polarity pulse into the circuit. Fast
troubleshooting includes injecting signals at key points in TTL. DTL, CMOS
or other popular circuits. Test with single pulse or 100 pulses per second
via built-in dual control push-button; button selects single shot or con-
tinuous modes. LED indicator monitors operating modes by flashing once
for single pulse or continuously for a pulse train. Completely automatic,
pencil-size lab/field pulse generator for any family of digital circuits. Out-
put: Tri state. Polarity: Pulse-sensing auto-polahty. Sync and Source: 100
mA. Pulse Train: 100 pps. LED Indicator: Flashes for single pulse; stays lit
for pulse train.

CSC Model DP-1 Digital Pulser-Net Each $7435 $71.20

MODEL LP-2

Economy version of Model LP-1 . Safer than a voltmeter. More accurate than
a scope Input Impedance: 300,000 ohms Minimum Detectable Pulse: 300
ns. Maximum Input Signal (Frequency): 1.5 MHz. Pulse Detector (LED): High
speed train or single event. Pulse Memory: None. _

CSC Model LP-2 Logic Probe-Net Each 5*4djf $23.70

MODEL LP-3

High speed logic probe. Captures pulses as short as 10 ns. Input Im-
pedance: 500.000 ohms Minimum Detectable Pulse: 10 ns Maximum Input
Signal (Frequency): 50 MHz Pulse Detector (LED): High speed train or
single event Pulse Memory: Pulse or level transition detected and stored.
CSC Model LP-3 Logic Probe— Net Each &Q35 $66.45

SD COMPUTER BOARDS

1B1MU&

$319 KIT"

VDB-8Q34 Video Display Board

With On-Board Z80 Microprocessor

$239 KIT

SBC-100 Single Board Computer

with On-board RAM, PROM, CTC

• Full 80 Characters by 24 lines ilispluy

• Characters displayed by High Resolu-
tion 7x10 Matrix

• Keyboard Power and Interface

• Composite Video Output

• Sepuratc TTL Level Synchronization
und Video Outputs

• 2K Bytes Independent On Board

• On-Board Z80 Microprocessor

• Glich Free Display

• 96 Upper and Lower Case Characters

• 32 Special Character Set

• 128 Additional user Programmable
Characters

• Full Cursor Control

• Forward and Reverse Scrolling
Capability

• Operates as an Independent Terminal

• Variable Speed Display Rale

• Blinking. Underlining. Field Reverse.
Field Protect and CombinaUons

$249 SH0SC

Z80 Starter Kit

• ZBOCcntraJ Processing Unit

• 1024 Bytes of Random Access Memory

• 8K Bytes of Available PROM

• Serial Input/Outpul Port with both
Synchronous and Asynchronous
Operation

• Parallel Input and Output Ports

A Complete Microcomputer on a Board

• Z80 Central Processing Unit with 158 • Two Bl-dirccUonal 8-blt I/O Ports(Z80-

Inst ructions PIO)

• (hi Board Keyboard and Display • Switch Selectable PROM or Monitor

• Kansas City Standard Cassette Restart

Interface * 2K Byte ZBl'G Monitor in ROM

• PROM Programmer Built on-board • Memory Examine and Change

• Expansion provision for two S- 100 • Port Examine and Change

C oiuievmn. • Z80 C IT' Kegisu: r Examine and Change

• Wire Wrap area for custom circuitry • Up In 5 Programmable Breakpoints

) • Single 5 Volt Operation when not • Single Step through RAM or PROM

programming • Audio Cassette 1-oad and Dump

• IK Bytes of RAM ( Expandable to 2K • Vectored Interrupts provided bv

Bytes) Z80-CTC and Z80-PIO

• IK Uytcs of RAM (Expandable to 2K • Ideal for Exjicrlmcnialon and

Bytes) Evaluating the Z80CPU

PRIORITY ONE ELECTRONICS

16723B Roscoe Blvd. Sepulveda, CA 91343

Terms: Visa, MC, BAC, Check, Money Order, C.O.D. U.S. Funds Only. CA residents add 6% sales tax. W
Minimum order $10.00. Prepaid U.S. orders less than $75.00 include 5% shipping and handling, T
minimum $2.50. Excess refunded. Just in case . . . please include your phone no.

Prices subject to change without notice.

We will do our best to maintain prices thru Sept. 1979. OEM and institut

phone orders welcome (213) 894*8171, (800) 423-5633 inquiries invited.

Visit our new retail location!

ORDER TOLL FREE 1-800*423-5633 ORDER TOLL FREE 1-800-423-5633

Visit our new retail location! Visit our new retail location!

HICKOK LX303 $74.95 HICKOK LX303 $74.95

RS232 & “D” TYPE CONNECTORS

Plug-Male S = Socket-Female C = Cover Hood

■ m ■

37 Pin Male
37 Pin Female
37 Pin Cover
50 Pin Male
50 Pin Female
50 Pin Cover
Hardware Set (2 pair)

PRICE

5-9 10-24
1.50 1.30 1.20
2.15 2.05 1.95
1.50 1.30 1.15
2.20 2.00 1.80
3.20 3.00 2.80
1.60 1.45 1.30

2.90 2.60 2.50
3.75 3.65 3.40
1.85 1.40 1.20

1.90 1.60 1.50
1.80 1.55 1.35
3.95 3.80 3.60

““ .20

HICKOK LX303 $74.95

3 LEVEL GOLD WIRE WRAP SOCKETS

Sockets purchased in multiples of 50 per type may be combined for best price.

C.V.V.V.V.V.*^ 5.75 5.50 5.20

7o\ 2.20 1.95 1.75

‘ r—— FEMALE — 1 * 495 4 75 4 50

7.50 7.20 6.90

2.50 2.20 2.10

1.00 .80 .70

Connector lor CENTRONICS 700 SERIES:

Amphenol 57-30360 for back of Centronics 700 Series printers
14 -$9 00 5-up -$7 50

.5%, 3 Vi digit 19
Range DVM. Vi” LCD displays
runs 200 hrs on 1 battery. 10 Meg
Ohm Input. 1 yr. guarantee, made in
U.S.A., test leads included.

Available Accessories

RC-3 115V AC Adapter $7.50

CC-3 Deluxe Padded Vinyl

Carrying Case $7.50

VP- 10 X10 DCV Probe Adapter/

Protector lOKv $14.95

VP-40 40 Kv DC Probe $35.00

CS-1 10 Amp Current Shunt $14.95

*FREE

Just for Asking.

FREE BATTERY with your meter.

^ S-100 BUS EDGE CONNECTORS

'S'

S100-WWQ 50/100 Corn .125 ctrs. 3
LEVEL WIRE WRAP 025" sq. posts on
250 spaced rows GOLD PLATED
1-4 5-9 10-24

$4.00 $3.75 $3.50

S100ALT 50/100 Cont. 125 Ctrs.
SOLDER TAIL on 140 spaced rows
ALTAIR motherboards. GOLD plated.

S100-STG 50/100 Coni 125 ctrs DIP
SOLDER TAIL on .250 spaced rows for
VECTOR, IMSAI. CROMENCO mother
boards GOLD plated.

1-4 5-9 10-24

$3.50 $3.25 $3.00

S100SE 50/100 Cont. 125 ctrs PIERCED
SOLDER EYELET tails. GOLD
1-4 5 9 10-24

$5.00 $4.50 $400

Other Popular Edge Connectors

02244- SSE 22/44Cont. 156 ctrs PIERCED
SOLDER EYELET tails. GOLD plated
1-4 59 10-24

$3.00 $2.60 $2.20

02244-SWW 22/44 Cont . 156 ctrs. WIRE
WRAP tails GOLD

1-4 5-9 10-24

$3.95 $3.70 $3 40

CG I IMSAI Style Card Guides 5/$1 00

See our July Ad for many other connectors.

1-9

10-24

25-99

100-249

250-999

8 pin

.40

.36

.34

.31

.27

14 pin

.39

.38

.36

.32

.31

16 pin

.50

.42

.40

.36

.34

18 pin

.70

.60

.55

.50

.45

20 pin

.90

.80

.75

.65

.62

22 pin

.95

.85

.80

.70

.65

24 pin

.95

.85

.80

.70

.65

28 pin

1.25

1.15

1.00

.95

.90

40 pin

1.65

1.45

1.35

1.20

1.10

All sockets are GOLD 3 level closed entry. 2 level Tail, Low

Profile, Tin Sockets and Dip Plugs available. CALL FOR QUOTATION.

,^js nrimrni nrmntnnr

r APPLE PLUGBOARD

Vector 4609 Peripheral Interface Plugboard for construction of custom circuits
Plug compatible with Apple II. Commodore PET and Super Kim microcomputers
Three connectors, in addition to the standard 25/50 system bus, are available for
input/output. A 20/40-contact card-edge connector, fabricated on the rear of the
board, mates with a 3-M type ribbon connector. Alternatively, a right-angle
solder-tail header may be positioned in this same location. The Model 4609 also
accomodates the miniature SIP-type connectors which may be placed on the
periphery or in mid-board.

1-4

5-9

10-24

$19.95 $17.96 $15.96

is 12

8803

MOTHER
BOARD FOR

unuium c*3 tu-
tors lor +5. +12.

— 12 Duses aria >nsu-

ijtefl mounting spicecs cinn RIIS

• Wiring side shown Com- 51U0 BUo

ponent side bare ebony M ICRO-

giass «Mti white markings to. COMPUTERS
component locations

• GtC epoiy glass board «ntn 2 ounce
copper solder plated and 038 diame-
ter holes lor leads

• Solder mas* with solder windows on
etched orewts to avoid accidental short
circuits

• Mounls 1 1 receptacles wlh 100 contacts <2
rows) on 125 centers with 250 row soacmg.

Vector part number R«8i 2. or mounts 10 -ecep-
lades plus interconnections to smaller mother board
tor eipansion

active pull-up. or floating terminations
• Large buses +5Vand GNO(IOAMPS). ♦ 12Vor 16V (7
AMPS) Current ratings are per MIL STD- 275 with 10*C

Price:

$29.50

Plugboards

8800V

Universal Microcomputer/processor
plugboard use with S-100 bus Com-
plete with heat sink & hardware 5 3“ x
10 x 1/16

1-4 5-9 10-24

$19.95 $17.95 $15.96

8801-1

Same as 8800V except plain: less power
buses & heat sink

1-4 5-9 10-24

$15.22 $13.79 $12.18

3682 9.6” x 4.5”
$10.97

3682-2 6.5” x 4.5”
$9.81

Hi-Density Dual-ln-Line
Plugboard for Wire Wrap
with Power & Grd. 8us
Epoxy Glass 1/16” 44
pin con. spaced .156

3677 9 6” x 4.5’

$10.90

3677-2 6.5” x 4.5”

$9.74

3662 6.5” x 4.5”

$7.65

Gen. Purpose D.l P. 3662-2 9.6” x4. 5”
Boards with Bus Pattern $11.45
for Solder or Wire Wrap. P pattern plugboards for
Epoxy Glass 1/16” 44 IC’s Epoxy Glass 1/16"
pi n cc n . spaced .156 44 p i n con . spaced .156

3690-12
CARD EXTENDER

Card Extender has 100 con-
tacts 50 per side on .125
centers-Attached connec-
tor-is compatible with
S-100 Bus Systems. $25.83
3690 6.5” 22/44 pin .156
ctrs. Extenders .... $13.17 .

1/16 Pectdt BOARD
.042 dia holes on
0.1 spacing for IC’s

Phenolic
PART NO.
64P44XXXP
169P44XXXP

Epoxy Glass
64P44
84P44
169P44
169P84

SIZE

4.5x6.5”

4.5x17”

4.5x6.5”

4.5X8.5”

4.5x17”

8.5x17”

PRICE
1-9 10-19
$1.56 $1.40
$3.69 $3.32

$1.79 $1.61
$2.21 $1.99
$4.52 $4.07
$8.03 $7.23

TRS -80/APPLE

MEMORY EXPANSION KITS
4116’s RAMS

from Leading Manufacturers

(16Kx1 200ns)

PRICE: $18.98

315-S same as 315
but with 14" bar to
accomodate "S100”
boards.

PRICE $1998

8 for $75.00

Add $3.00 for programming Jumpers
for TRS-80 Keyboard

HitSEl

SE Jgin

$13.49

PRICE: $13.49
VACUUM BASE

PRICE: $14.49

PANAVISE TILTS, TURNS, AND * ’gST
ROTATES TO'ANY POSITION. *— *

IT HOLDS YOUR WORK
EXACT^^HER^rOL^ANT IT.

PRICE: $18.49

PRICE: $14.49

-Mi

1C SOCKET SALE

14 pin Low Profile
m2. 10 100/$14.00
16 pin Low Profile
10/S2.20 100/$16.00
24 pin Low Profile
3/$1.0Q 4O/$1O,0O
40 pin Solder Tail
3/$1 .00 40/$10.00
24 pin Dip Plug with
cover

3/SI .OQ40/$10,QQ

.si

14 & 16 PIN

'GOLD 3 LEVEL
WIRE WRAP
SOCKES

14 - G3 100 for
$33.00
16 * G3 100 for
$33.00

50 of each for $35.00i

MEMORY MEMORY

2102LIPC Low Power 450ns in lots of 25 $1-10
2102AL-2 Low Power 250ns in lots of 25 $1.25
211 4-3L 1 Kx4 300 ns Low Power 8/$50.00
5257-3L 4Kxl 300ns Low Power 8/$5 0.00

2708 8K 450ns EPROM $9.00

2716 t6K 5 Volt Only EPROM $45.00

WRA£ POST

for .042 dia. holes

I (all boards on this page) \
T44/C pkg. 100 . . $ 2.34
T44/M pkg.

1000 $14.35 *

I A-13 hand installing

tool $ 2.94 .

PRIORITY

16723K Roscoe Blvd

Yk&r Perfectly bala

u/ith nrarlaim

ONE

IM-10A List $89.00'
SPECIAL
$56.95 with tube

balanced fluorescent lighting
with precision magnifier lens. Tough
thermoplastic shade. Easy lens re-
moval. New wire clip design permits
easy installation and removal of
fluorescent tube. Comes with plastic
shield to protect tube from soiling and
damage.

Colors: Gray, Black, and Chocolate Brown.
Comes with one 22 watt T-9 Ctrcllne fluores-
cent tube. 3 diopter l ens.

ORDER TOLL FREE

1 800 423 56331

except CA., AK„ HI., Ceil

(213) 894-8171

7 ELECTRONICS

Sepulveda, CA 91343

Terms: Visa, MC, BAC, Check, Money Order, C.O.D. U.S. Funds Only. CA residents add 6% sales tax.

Minimum order $10.00. Prepaid U.S. orders less than $75.00 include 5% shipping and handling
minimum $2.50. Excess refunded. Just in case . . . please include your phone no.

Prices subject to change without notice.

We will do our best to maintain prices thru Sept. 1979. OEM and Institutional

phone orders welcome (213) 894*8171, (800) 423-5633 inquiries invited

TEST

EQUIPMENT
CALL FOR
SPECIAL PRICES

ORDER TOLL FREE 1-800*423-5633 ORDER TOLL FREE 1-800-423-5633

HICKOK LX3Q3 $74.95 HICKOK LX303 $74.95 HICKOK LX303 $74.95

i ADVANCED l ^~"

COMPUTER

ts A38

fPRQDUCTS

RAM BOARDS

S-100 32K (uses 2114)

ASSEMBLED Kit

450ns. 599.00 450ns. ' 539.95

250ns. 699.95 250ns. 59995

Bare Board 49.95

Bare Board w/all parts less mem. 99.95

S-10016K (uses 21 14) KIT (exp. to 32K)
ASSEMBLED 450ns. 279.00

450ns. 325.00 250ns. 299.00

250ns. 375.00

Bare Board 49.95 ^

LOGOS I 8K fW WBKi l

ASSEMBLED /

450 ns. 169.95 KIT 450ns. 125.95

250ns. 189.95 250ns. 149.95

Bare PC Board w/Data $21.95
Now over 1 year successful field experience
“Special Offer" Buy (4) 8K 450ns. Kits $1 17.00

FLOPPY DISK DRIVES

1. VISTA V-80 MINIDISK
FOR TRS-80

★ 23% More Storage

Capacity - 40 T racks

★ 40 track patch now avail.

★ Faster Drive • *

Up to 8 Times Faster l 395.00

2 Drive Cable Add $29.95
4 Drive Cable Add $39.95

2. VISTA V-200 MINI-FLOPPY SYSTEM

★ 204 K Byte Capacity ★ w/CP M, Ba sic “E"

★ Double Density Drive

★ One Double Density ( V-200 N
Controller w/Case & P.S \699.00 /

Add to your EXIDY, HORIZON,
and other S-100 computers.

3. VISTA V-1 000 FLOPPY DISK SYSTEM

★ (2) Shugart 8” Floppy Dis ks _

★ Controller Card, Cable,

Case & P.S.

★ CPM & Basic “E’, U6®».0«

Instructions & Manual S

4. MPI B51-5y4”. 40 tracks 279.00

5. Shugart SA400-5V4”, 35 tracks .... 295.00

6. Siemens/GSI FDD10O-8 8” 375.00

7. Shugart 800/801 R 8” 495.00

8. PERSCI Model 277 Dual 1195.00

9. WANGO/SIEMENS 5^.” Drive . . . 290.00

EXPANDORAM MEMORY KITS

★ Bank Selectable ★ Uses 41 15 or 41 16

200 ns.

★ Write Protect ★ Power 8VDC, ±16VDC

★ Phantom ★ Lowest Cost/Bit

Expando 32 Kit (4115) Expando 64 Kit (4116)

8K $158.00 16K $248-95

16K $199.00 32 K $369.00

24 K $299.00 48K $469.00

32 K $349.00 64K $565.00

IMS STATIC RAM BOARDS

★ Memory Mapping ★ Low Power

★ Phantom ★ Assembled & tested

Recommended by Alphamicrosystems

250 n s. 450 ns .

8K Static $209.00 $189.00

16K Static $449.00 $399.00

32 K Static $799.00 $699.00

ANADEX PRINTER

Model DP-8000 compact, impact, parallel or
serial. Sprocket feed, 80 cols,
84 lines/min., bi-directional.

I New only $895.00

VERBATIM™ DISKETTES 0 >M

★ 5V4” Minidiskettes ★ o

Softsector, 1 0 Sector, 1 6 Sector
$4.25 Each, 1 0/39.95

★ 8” Standard Floppy Disks ★

Soft Sector, Hard Sector v'

$4.50 Each, 10/41.95

*Add 4.95 for 1 0 Pack in Deluxe Disk Holder

MOTOROLA EXORCISER COMPATIBLE

9600 MPU Module w/6802 CPU $495.00

9601 16 Slot Mother Board 175.00

9602 Card Cage (1 9” Retma Rack Mount) . . .75.00

9603 8 Slot Mother Board 100.00

9604 Switch mode System Power Supply .... 250.00

9610 Utility Prototyping Board 36.00

9616 Quad 8K Eprom Module ***

9620 16 Channel Parallel I/O Module ... 295.00
9622 Serial/Parallel I/O Combo ***

9626 8K Static RAM Module 295.00

9627 1 6K Static 450ns 495.00

9630 Card Extender 68.00

9640 Multiple Programmable Timer

(24 Timers) 395.00

9650 8 Channel Dupiex Serial I/O 395.00

961 03 32/32 I/O Module 275.00

96702 32 Point Reed Relay Module 350.00

6800 BARE BOARDS

9620-0 $45.00 9603-0 27.00

9626-0 45.00 9600 55.00

9650-0 45.00 96103 55.00

9601 -0 50.00 96702 55.00

Also AMI EVK System in Stock

TRS 80 TO S-100

PET TO S-100 ADAPTER

Allows Pet/TRS 80 to be interfaced to

popular S-100 Bus.

Pet to S-100 Kit

$189.95

Assembled

$269.95

TRS80toS-100 HUH 8100 Kit ....

$275.00

Assembled

$355.00

APPLE/EXIDY/EXPANDO
TRS 80 16K-UPGRADE KIT

★ 16K with Jumpers & Instructions

for either Level I or Level II $74.95

★ 16K for Apple II Upgrade $74.95

Special: TRS80 Schematic $ 4.95

Expansion Interface Schematic — $ 4.95

KEYBOARD ASCII ENCODED

One time purchase of
* NEW Surplus key-
boards. From the Singer
Corporation. The
I keyboard features 1 28
“ASCI I characters in a 63
key format, MOS
encoder circuitry “N" key I
rollover, lighted shift lock, control, escape and I
repeat functions. Ltd Qt y 63 KEY $59.95

UV “Eprom” Eraser

Model UVs-1 1 E $69.95 I

Holds 4 Eprom’s at a time.|
Backed by 45 years
experience.

Model S-52T. . . $265.00 |

Professional Industrial Model

TARBELL FLOPPY INTERFACE

★ Z 80/8080 S 100 Compatible * Uses CPM

Assembled for Shugart SALE $229.00

Assembled Other Drives S269.95

Kit SI 79.95 j

Bare Board $36.95 (Doc. Add $10.00)

Note: For CPM Add S70.00. Documentation Add $20.00

Vista Double Density 5V-T Controller Assem $299.00

SD Versa Floppy Kit $1 59.95

SD Versa Floppy Assembled $1 89.95

Tarbel Cassette I/O Kit $11 5 00

Sale* 1771-01 Floppy Chip $27.9, r

BYTE USER 8K EPROM BOARD

★ Power on Jump ★ Reset Jump

Assembled & Tested $94.95

Byteuser Kit $64.95

Bare PC Board $21 95

Special Offer: Buy 4 kits only $59.95 each

MR-8 8K w/1 K Ram $99.50

MR-1 6 1 6K w/1 K Ram $99.50

EPM-1 4K 1702 $59.95

EPM-2 2708 or 27 1 6 E^ >m $69.95

Z-80/Z-80 A/8080 CPU BOARD

★ On board 2708 ★ 2708 included (450ns.)
*■ Power on jump ■* completely socketed

Assembled and tested $185.00

Kit $129.95

Bare PC Board $ 34.95

★ For 4MHz Speed Add $1 5.00

8080A Kit $ 99.95

8080A Assembled $149.95

S-100 MOTHERBOARD SPECIAL

8 slot expandable w/9 conn.

reg $69.95 NOW $52.95

TARBELL FLOPPY CONTROLLER

Card assembled and tested for use with Shugart
Drives $ SALE PRICE only $229.00

ACOUSTIC MODEM

NOVATION CAT™

0-300 Baud

Bell 103 __

Answer, Originate $198.00

ACOUSTIC COUPLER SPECIAL

AJ MODEL A30
SPECIAL PURCHASE
OF SURPLUS UNITS
AVAILABILITY LIMITED $29.95

DATA BOOKS • COMPUTER BOOKS

1 979 1C Master 49.95 Intel MCS 80 Manual. . 7.95

NSC TTL Data 3.95 Intel MCS 40 Manual 4.96

NSC Linear 4 95 AMD 8080A Manual 5.95

NSC Linear App Notes II . 3.95 AMD Sehottky Databook 4 95

NSC CMOS 3.96 AMI MOS/LSI Data 3.95

NSC Memory 3.95 Gl MOS/LSI Data 4.95

Intel Databook 4 95 Hams Analog Databook 4.95

Intel MCS 85 Manual 7 50 T1 Linear Control Data 3.95

SALE • OSBORNE BOOKS • SALE

Intro to Micros Vol. 0. . .
Intro to Micros Vol. I . . .
8080A Programming. .

6800 Programming

Z80 Programming

..■BiM 7.76
..fcSO 7.75
..frSQ 775
..$SQ 7.75

..foQ 7 75

Vol. II Some Real MicroprocessO'S w/Bmder 39-GO 27.50

Vol, III Some Real Support Devices w/Binder. WOO. 18.50

Intro to Micros Vol. Ill TOGCi 18 50

SALE • DILITHIUM COMPUTER BOOKS • SALE

Understanding Computers *8-96. 7.95

8080Microcomputer Experiments Tj-gs. 1 1.95

Beginning BASIC ... 9GS. 8 95

Beginners Glossary & Guide ML 596

Peanut Butter & Jelty Guide to Computers -T9L. 6 95

8080 Machine Language Program m ng T-9S. 6 95

Home Computers Vol. I Hardware T-96 6.95

Home Computers Vol. II Software T9G6. 1 1.95

Starahlp Simulator T/9»~ 0.95

O. BOX 17329 Irvine, California 92713

THE FIRST TO OFFER PRIME PRODUCTS TO THE HOBBYIST
AT FAIR PRICES NOW LOWERS PRICES EVEN FURTHER!

1. Proven Quality Factory tested products only, no re-tests

or fallouts. Guaranteed money back. We stand behind our products.

1979 CATALOG NOW AVAILABLE.

Send $1 .00 for your copy of the most complete catalog of computer products. A must
for the serious computer user.

MICROPROCESSORS STATIC RAM HEADQUARTERS

Z8000 $ CALL

2 80

Z-80A
F-8 (38501
2650
CO 1802
6080A
8080A-4MHI
SALE 8085
8008-1
290 1
2901 A
TMS 9900JL
CP1600
6502
6502A
IM6100

6802 P
6035
8755 ....
8748

14.99

16.95

18 95

17.95
9 95

1995

19.99
14 95

12.95

19.95

49.95
39 95
11.50

19 95
29 95

.. 1395

24 95
1995
49 95
69 95

..SCALL

8086 SCALL

SUPPORT DEVICES

AM95 1 1 Arith Processor S 1 95 00

AM 951 1-1 300 ns 245.00

AM95 1 7 DMA Controller 7 1 95
AM95 1 9 Universal Interrupt 24 95

3881 (Z80 PlOl 9 95

388i4i4MHzi 14.95

3882 lZ-80 CTC» 9.95

3882-4 |4MHzt 14.95

3883 SKD 29.95

3884 DMA..

8265 74S 138 Decoder

82t2 8 bit I'O

82 1 4 Priority Ini

82 1 6 Bus Driver

8224 Clock Gen

8224-4 I4MHZI

8226 Bus Onver

8T26 Bus Driver

6228 Sys Control

6238 Sys. Coot

8251 Prog I/O

8253 Int. Timer

8255 Prog 1,0

8257 Prog DMA

8259 Prog Int

8275 CRT Controller

8279 Prog Keyboard

6810-1 128 x 8 RAM

6820 PIA

682! PIA

6828 Priority Ini

6834-1 512x8 Eprom

6850 ACIA

6852 Serial Adapter

6845/HD46505CRTCnnrr

6860 Modem

6882 Modulator

6871 A 10MHz OSC

6875

6680 Bus Driver
MC68488.

1821 SCO IK RAM

1822 SCD 256x4 RAM
1824 CD 32x8 RAM
1852 CD 8 bit I/O

49.95
2 95
2 50
450
2 50

2 95
9 75

3 95
2 39
5.95
&M
6 95

1950

5.95

17.95

49.95
16 95

475

5.96
6.60

8.95
12 95

5.95
595

39.95
8 95

11 95
2595

8 25
2 39

19.95
2500
16 95

9 95
10 95

1854 Uart 10.95

8 95
895
750
925
1550
1550
1550
15.50

1856 CD I/O

1857 CD I/O
6520 PIA
6522 Mult
6530-002
6530-003
6530-004
6530-005

DYNAMIC RAMS

416/4116 16K (16 Pin) '9.95

Set 018 416 s 74 95

41 15 8K (16 Pin) 6.95

4050 4K x 1 (16 Pin) 4,25

4060 4Kx 1 (22 Pm) 4 95

4096 4Kx 1 (16 Pm) 3.95

2104 4Kx 1 (16 Pm) 475

4027 4K x 1 (16 Pin) 4.95

5261 1.95 1103. 1 95

5262 1.95 4008L 4 95

5270 4.95 6605 7 95

5280 4.95 6604

5290. ...1245 6002

PROMS

2708
2708-6
1702A

2732

2716-5V
2716-5V. 12V
2758 5V
5203AO
5204AO
6834-1
IM 5610

SALE 8223 32 x

14.95
1075
1075
14 50

2513-ADM3(5V) Lower
MCM6571
MCM6571A
MCM6574
MCM6575

UARTS/USRTS

TR1602B (5V. 12V)

AY51 01315V. 12V)

AY51014A/1612 I5-14V)
AY51015A/1863 15V)

TMS 6011 15V 12V)

IM6402
IM6403
2350 USRT
167 IB Astros
SALE TR1472B 9.95

3 95
495
695
6 95
5 50
795
895
995
24 95

BAUD RATE GEN

MCI 441 t

4702

WD1941

11.95
14 95
9 95

KEYBOARD ENCODERS

AY5-2376 13 75

AY 5-3600 1375

HD0165 9 95

74C922 9.95

74C923 9 95

A/D CONVERTERS

8700 8 bit Binary

8701 10 bit Binary
8703 8 bit TS.

9400 Volt to Freq Cortv
8750 3-1/2 Digit BCD
1408L6 C bil
1408L8 8 bit
DACOI A/D

13 50
22 00
13 50
7 25
1395
3 95
5 95
5 95

21 L02 450ns
21L02 250ns
2102
2111
2112-1
2101-1
2114L-250ns
21 14L-300ns.

21 1 4L-450ns.

4044/4041 300ns.

1 25
3 75

2 95
290

1295

895

7.50

9.95

3 65
285
270
1095
7.95
675
a 75
6.75
875
7 25

4044/4041 450ns. 7.50

EMM4200A 975

EMM4402 7.95

EMM4604 12.50

5101C-E 7 95 7 95

upd41 0(4200) 10 95 10 25

AMDS) 140.-4 1 10 95 10 25

AMD9 130/31 12 95 1195

FSC 460 4641 6K CCD Only $1895 Each
1181 195 '175

P2 125/93425 145 ns I 7 95 7 35

6508 IK xl CMOS 7 95 7 95

6518 IKxl CMOS 7 95 7,95

74S189 64 bit Ram 3 95 3.25

8155 I/O w/Ram 2195

17 Low Power 4K Static 14 95ea

1.45
1.10
3.56
265
2 55
9.95

6.45
4.75
795
4.75
7 95
625
9.95
7 25
9 25
9 25

10 25

CHARGE COUPLED DEVICES

16K CCD - First time ottered Fairchild 460 CCO
16K Memory (now you can experiment with CCD
technology at a reasonable price 1 7 page Applica-
tion note supplied with each order Quantity limited)

$18.95 each (r 9 g. 43.00)

CRYSTALS

Microprocessor Timobasos TV Game
Frequency Price Frequency Price

1 0MHz S5 65 60MHz S 4 95

1 8432 4 95 6 1 44 4 95

20MHz 5 85 6 5536 4 95

201MHz 295 100MHz 495

2 097152MHz 5 85 13 0MHz 4 95

2 4576MHz 5 85 14 31818 4 95

3 579545MHz 150 18 0MHz 4 95

4 CMHz 4 95 18 432MHz 5 95

4 194304MHz 595 200MHr 4 95

4 91520MHz 5 95 22 1184MHz 5 95

5 0MHz 4 95 27 0MHz 595

5 0688 4 95 36 0MHz 5 95

5 7143MHz 5 95 48 0MHz 5 95

100KC 12 95

DISPLAYS/OPTO/LED’S

* 7 SEGMENT * CALC * CLOCKS *

DL 704 (CC). DL 707 |CA) .300“ Red 99

FND 357 ICC) .357" Red 99

FND 500/503 (CC) .500- Red 99

FND 507/510 (CA) 500" Red 99

FND 600/803 (CC) .800" Red 1 .75

FND 807/810 (CA) 800" Red 1 75

XAN 3062 .500" Green 1.15

HPS082-7731 (CA) 300" Red 99

9 Digit Bubble Mini Calc. Display 99

9 Digit Panaplex Display .400" 99

9 Digit Fluorescent .300" 99

MAI 003 12V Auto Clock Module 16.95

Bezel for MAI 003 w/Red Filter 4.95

MAI 002 A LED 12 hr. Clock Module 10.96

* HEX DISPLAYS * ENCODED DISPLAYS *

HP 5062-7340 Red Hexidecimal 1 5.95

HP 5082-7300 Red Nymenc 14.95

TIL 306 Numeric w/Logic 8 95

TIL 308 Number w/LogiC B 95

TIL 309 Number w/Logic 8.95

TIL 31 1 Hexadecimal 1 2.95

MAN 2A .320" Red Alpha-Numeric 5.95

MAN 10A .270* Red Alpha-Numeric 8 96

SOCKETS

8 Pm WArfV 32
1 4 Pm W/W 37
16 Pm W/W 38
18 Pin W/W 60
2C Pm W/W

8 Pn S/T 17
14 Pn S/T 20
1 6 P n S/T 22
18 Pn S/T 31
20 P n S T 34

40 Pm W/W 1 49 40 Pm S/T 63

TEXTOOL ZERO
INSERTION FORCE
SOCKETS

16 Pm $ 5 50 24 Pm $7.50

CONNECTORS

DB25P (RS232) 3 25

DB25S Female 3 75

Hood 125

Set w/Hood. Sale $6 50

22/44 W/W. S/T. KIM 2 95

43/86 W/W. S/T. MOT 6 50

50/100 S-100 Connector w/w . . 4 25
50/1 00 S- 1 00 Connector s/l 3.25

CTS DIPSWITCHES

CTS206-4 $1.75 CTS206-6 $1.95
CTS206-5 $1 75 CTS206-9 $1 95

CTS206-6 SI. 75 CTS206-10 $1 95
CTS206-7 $1 75

NAKED PC BOARDSALE

Z-80 CPU (Ithaca)

: 14 35

8080A CPU

■4 35

8K Static RAM (Logos)

16K Static RAM (21 14)

23 95

32K Static RAM (21 14)

4-95

Floppy I/O (Tarbeil) .

39 95

Cassette I/O (Tartoeii)

29 95

8K Eprom (2708)

21 95

1702 Eprom Board

-■C OC

2708/2716 Eprom (Khacal

34 95

2708/27 1 6 Eprom (WMC) .

30 JO

Realtime Clock

34 i *

ACP Proto Bd. (3M Conn.) .

27 95

Vector 8800 Proto

1995

Vector 8803 1 1 slot MB

ACP Extender w/Conn

•5 9b

Video Interface (SSM) ....

•-

Parallel Interface (SSM)

27 95

1 3 Slot MotnerBoard i\VMC) 32 95

9 Slot Mother Board (WMC)

- -95

8 Slot Mother (expandable)

34 95

WAVEFORM

GENERATORS

8038 Function Gen. 3 95

MC4024 VCO 2 45

LMS66 VCO 1 75

XR2206 Function Generator 5 25

FLOPPY DISK I/O

1771-01 8“ ft Minifloppy 27 95

uPd372 Nec Flopoy 49 95

1781 Dual Floppy 29 95

1791 Dual Floppy 39.95

TV INTERFACES

Pixie-Verter

TV-1 Video Interlace

Microverler

MSR Modulator

8 50
8 95
35 00
3500

495

9 95
7.50
395
99.00

9 95
12 95
2 95

2.95

82S1 15 512 x 8 (TS) 16.95

82S123 32x 8 2.50

82S126 256x4 3 50

82S1 29 256 x 4 (TS) 3=50

82S130 512x4(00 6.50

NSC DM7578 32 x 8 2 95

CHARACTER GEN

SPECIAL PURCHASE
(while supply lasts)

21 L02-4 (450 ns) 100 @ 99$ ea.

21 L02-2 (250 ns) 1 00 @ $1 .1 5 ea.
TMS4060 NL 4K Dynamic RAMS
(pullouts) $1.95 ea.

1488 Line Receiver 100 @ 75$ ea.

1489 Line Driver 100 @ 75$ ea.
1489 House Marked 100 @ 500 ea.
1496 L Demodulator 25 @ 75$ ea.

COMPUTER SPECIALS

SALE

Apple II Plus w/1 6K

1195.

990.

IPSI 1620 Diabie RQ3295.

2695.

PET 2001-16N

995.

895.

Anadex DP 8000

995.

895.

Exidy Sorcerer w/8K

895.

795.

Centronics Micro P-t

595.

395.

Compucolor II w/8K

1495.

1395.

Centronics Micro S-1

595.

525.

Cromemco Sys III

5990.

4990.

Soroc IQ 1 20

995.

850.

Horizon 1 w/16K

1599.

1349.

Teletype Model 43

1349.

1150.

TEI PI208 w/32K

HiPlot Plotter

1085.

899.

dual floppy & CRT

HiPlot Digitizer

795,

735.

(1 avail.)

4995

2995

Interlube II

895.

784.

Pascal Microengine

2995

2395

* LED's * OPTO ISOLATE RS *

LEDS Red. Yellow. Green .185 5/1,00

MCT 2 Photo XSTR HFE 250, 30V 99

4N25 Photo XSTR HFE 250, 30V 1 29

4N33 Photo Darlington 1 75

FPT 1 10B Photo XSTR Flat Lense SALE 4/1 .00

MONTHLY 1C SPECIALS

LF 13506 JFET Anloq Multi 8 bit 8.95

ICM7208 Seven Decade Counter 1 7.95

ICM7207 Oscillator Controller 6.95

ICM7045 Precision Sto/Watch Timer 22.95

ICL7107 3V, Digit A/D (LED) 14 95

ICL821 1 Voltage Reference 1 .95

LM390 Battery OP. Audio Amp 3/1.00

LM 1850 Ground Fault 1C 3/1 00

LM 1 800 Phase Lock Loop FM Stereo 3/1 .00

LM 1820 AM Radio 3/1.00

DS3625 Dual Mos Sense Amp 2.50

1408L8 4/19.95 10147ECLRam .. . 9.96

1488/1489 2/1.99 LF356HBIFet . . 3/1. 99

22 Pin S/T Socket 10/1.00 MCM14505 8 95

8223 Prom . . . . , 2 95 74S89 3/1 99

MK5014 Calc 2/1 99 74107N 6/199

74141N 3/1.99 75452N 8/1.99

8T26/8T28 2.39 741N-14 10/199

95H90 9.95 555CN 5/1.99

8281 50 5S6CN 3/199

TV CHIPS/SOUND

AY38500-1 6 Games B/W $4.95
AY38515 Color Converter 2 95
AY38603-1 Roadrace Game 8 95
AY38605- 1 Warfare Game . 9 50

AY38606-1 Wipeout Game 9.50
AY38607-1 Shooting Gallery 8 95
AY38910 Gimm, Cricket Sound

Generator 1 2.95

SN76477 Tl Sound Generator 3 95
MM 5320/2 1 TV Synch Gen 9 95
MM5369 Prescaler 3 95

LM1889RF Modulator 3 95

MM571000 NSC Color TV

Game 6.95

MM571 04 Clock Gen . .... 3.75

RF Modulator w/Audio 8.95

All Shipments FCM or UPS. Orders
under $ 1 00 00 add 5% handling and
postage. Orders over $100 00 add
2 5% handling ft postage Master-
charge/ R of A /American Express/
COD accepted w/25% deposit.Cali-
torma Residents add 6% tax Foreign
Orders add 8% handling All parts
pnme factory tested guaranteed.
Add .35 cents for Data
Retail pricing may vary from Mail
Order Pricing AH pricing subject to
change without notice

Phone (714) 558-8813

TWX: 910-595-1565

Retail Store Open Mon. - Sat.
Located at 1310 "B" E. Edinger,
Santa Ana, CA 92705

tS Reader Service— see page 227

Microcomputing, October 1979 217

CAT-100 GETS

COLOR!

Complete on two S-100 boards,
CAT-100 is the original 16-color
imaging system with high
resolution video frame grabber.
FREE CATALOG stock.

request yours today 72 HR. SHIPMENT
Video out: 4-bit 0/A

16 levels or 16 colors Video in P u,: ,ul1 s P eed Expandable 32K byte
3 RGB color oulpuls \ 4 bl ' #/ ° . iml « e

Key

Electronics

<§x£<d>

Full ASCII Professional
Keyboard Kit, Model 756

Model 756 Keyboard Kit

$64.95

Model 701 Plastic Enclosure

14.95

Model 702 Steel Enclosure

29.95

Model 710 Numeric Keypad

9.95

2376 Keyboard Encoder 1C

9.95

15 pin Dual edge connector*

1.95

*(FREE with ALL keyboard orders)

INTEGRATED CIRCUITS:

SN76477N Complex Sound Generator

$2.95

TL489C :Analog Level Detector

1.25

LM317T Adj. Volt. Reg. 1.5 amp

2.75

ICM7555 Low Pwr. CMOS Timer

1.25

LF351N High Speed JFET Op Amp

.75

NE565 Phase Locked Loop

1.10

FREE: CA3 I 40 with orders of $5.00 or more
Please include $1.00 for postage and handling

N.Y.S. Residents Add 4% Sales Tax

Send to: Key Electronics

P.O. Box 3506

Schenectady, NY 12303 ^ K14

IBM SELECTRIC
BASED I/O TERMINAL
WITH ASCII CONVERSION
INSTALLED $645.00

e Tape Drives e Cable
e Cassette Drives e Wire
e Power Supplies 12V15A, 12V25A,
5V35A Others, e Displays
e Cabinets e XFMRS e Heat
Sinks e Printers e Components
Many other items
Write for free catalog
WORLDWIDE ELECT. INC. ^W16
130 Northeastern Blvd.

Nashua, NH 03060

Phone orders accepted using VISA
or MC. Toll Free 1-800-258-1036
In N.H. 603-889-7661

r TRS-80 1

MORE THAN 150 RFII's HA VE BEEN SOLD SO FAR ,
WHY?

* Internal speaker allows you to hear CIOAD and CSAVE * Fast lorward and rewind can
be heard (CTR-41) * Volume control to adjasl without affecting data level * Two LEDs in-
dicate the status ol the computer and recorders * Simultaneous CSAVE with two recorders

* CLOAD with either recorder * Cross tape with two recorders ‘ No more pulling cables *
Hatches TRS-80 "look" * You MUST be satisfied or return the RE II and receive all your
money back, including postage! ’ See review in March 1979 Creative Computing, page
28*

9-5 PM (805) 968-4266

Completely assembled ior CTR-41
for CTR 80 or CTR-21

For kit deducl 812. CA res. please include lai

$49.95

54.95

Please add 52.00 for shipping.

FULLER electronics
7465 Hollister suite 232
goleta, ca 93OI7

A A A A A A A.rt AAAAAAAftAAAAAAA

TRS - 80

INTRODUCTORY SPECIAL
Double Disk Drive

w/Case & Power Supply

$71 5.00 kw

4 Drive Cable $45.00
2 Drive Cable $35.00
Diskettes $29.00 Box/10

Diskettes $39.00* Box/10

Guaranteed 1 Year

Diskettes + $2.00 ups
Drives + $5.00 ups

HARDWARE - 80

P.O. Box 20194
1 Detroit Ml 48220 ^H46

MC/VISA

vvvvvvvvvvvuv/uuvvvvvvvv

ATTENTION

NORTH STAR USERS

TFS—

Text formatting system. At last a powerful, full-
featured text processor for the Northstar Disc
System!! ‘TFS” runs with virtually any system
configuration and any terminal. (Note: Uses
RAM from 0 to 2000H). Justifies left and right
margins, page and chapter headings, page num-
bering, multi-copy, move text, search text, sub-
stitute, merge files, and append files from disc,
and much much more! “TFS” is of great use by
anyone that wants perfect text and typing with
the minimum effort! Includes a 35-page user’s
manual complete with examples, plus a handy
quick reference guide to the “TFS” commands.

= = = > > $75.00

• TINY PASCAL: The Chung/Yuen Tiny Pascal includes ob-
ject and source! Needs only 24K to run!

“This is a great package!” = = = > > S40 oo

• ARIAN 0080(7 80 Operating System Assembler Text
Editor Debugger Dynamic File Capabilities Save & Load
Source/OBJ Files to Disk Resident and Custom Com
mands Truly a powertul. yet easy to use Operating System

= = = > ' S50 00

Plus much, much more, write for catalog.

(Illinois residents add 5% sales tax)

217-344-7596 "

P.O. Box 1 628. Champaign, I L 61 8201

PET PERIPHERALS

(FOR OTHER IEEE 488 BUS COMPUTERS, TOO)

NEW - RS-232 INTERFACE: $229

The TNW-2000 Bidirectional Serial Interface allows
keyboard input as well as printer output. The unit
provides selectable automatic PET/ASCII character
conversion, “throttled" output, baud rate adjustable
from 1 1 0 to 9600 bits per second. $229 price includes
power supply, cabinet, PET/IEEE cable, built-in female
EIA connector, full documentation. (For software
controllable RS-232 control lines, and multiple RS-232
devices, TNW offers the TNW-232D Serial Interface.
Price is $369, includes power supply, cabinet, PET
cable, full documentation.)

MODEM

The TNW488/103 Low Speed Modem is Bell 103
compatible, provides auto originate/answer/dial capa-
bilities. 75 to 600 bits per second. Interfaces to phone
system via DAA. Price of $389 includes power supply,
cabinet, cable to PET. full documentation, and software.

TNW

Corporation

«^T56

Ask your dealer or contact —

TNW Corporation • (714) 225-1040
5924 Quiet Slope Drive • San Diego, CA 92120

( ^flPPLE )

SUPER SALE

16K Apple II $1019.95

or Apple II Plus
Apple Disk II

w/controller $529.95

Apple Soft Cards $159.95
Pascal Language Card $459.95
10 Megabyte Disk
for Apple $4695.00

DC Hayes Modems $339.95

ucfliiRn rampuTEPi store

Across from Ramada Inn

P.O. Box 1000 *' ui0

Destin, FL 32541
904-837-2022

Credit Cards Accepted

218 Microcomputing, October 1979

• Test Equipment

• Power Supply Components

• Power Supplies

• Communication Equipment

• Pulse Equipment

f _ *^ S16 TELEPHONES:

SEtECT&OA// C =

1206-18 S. Napa Street

1206 S. Napa Street • Philadelphia PA 19146

Penna. resident please add 6% sales tax. All prices are F.O.B. our warehouse, Phila. PA. All merchandise accurate as to
description to the best of our knowledge. Your purchase money refunded if not satisfied. Min. order $10.00

CABLES

5’ RG/59U cable with PL259 connector on one end.
Price: $1.00 ea. 6/$5.00

24” RG/59U cable with PL 259 connector on one
end, BNG on other end.

Price: $1.00 ea. 6/$5.00

MEMORY CHIP

Static Ram IK x 4 single 5 V power supply, single
phase TTL level clock, four chip select inputs with
data sheets included
Price: $3.50 ea. or 15/$40.00

ASCII KEYBOARD

61 key 7 bit plus strobe and parity. Positive logic
generates all 128 ASCII characters plus all 32 func-
tion codes. Operates on 5 volts. With data
Shpt. Wt. 3#

Price: $25.00 ea

CASSETTE DECK

Standard Phillips type cassette no capstan, reel to
reel drive with tachometer control, rewind 300 ft.
tape in 60 sec. BOT and EOT sense, also cassette
in, door closed and broken tape indication.

Shpt. wt. 5#

Price: $40.00 ea.

ALL ITEMS ARE REMOVED FROM EQUIPMENT

— S£lECT#Ofl//C$

Does it again .... high quality Sylvania monitors at the lowest prices ever. These
monitors have been thoroughly checked and guaranteed.

MONITORS

12” black & white monitor. Wide band, will display
80 x 24 char. 10K or 75Q input impedance, com-
posite video input. Transformer power supply.
Shpt. Wt. 30#

Price: $45.00 ea.

Used with all computers such as: TRS-80, Apple,
and many others.

KEYBOARDS

51 key typewriter style keyboard, with case, not en-
coded. Single contact keys
Shpt. Wt. 10#

Price: $10.00 ea.

SPECIAL

Microprocessor Chips #6502
Price: $6.00 ea. or 2/$10.00

REGULATED DC POWER SUPPLIES
MFGS. LAMBDA 8. NORTH

VOLTS

-AMPS

WT.

62#

PRICE

$40.00

35.00

30.00

25.00

20.00

30.00

35.00

DIGITAL DISPLAY BOARDS

6 digit numeric display boards with 6 FND 507.
Common anode displays and 10 red LED’s. With
drivers & logic for multiplexed operation.

Price: $5.00 ea. or 6/$25.00

y* Reader Service— see page 227

Microcomputing, October 1979 219

encyclopedia op
ralcRocorapattoe

4 ,600

That’s the size of the world’s most comprehensive guide to microcomputing. Over 2
years of Kilobaud Microcomputing a virtual expanding encyclopedia of com-

puting.

Back issues of Kilobaud Microcomputing are a gold mine of interesting articles.
There’s little to go stale in microcomputing . . . software, applications, great
editorials. Start your encyclopedia today by sending for our FREE KB Microcom-
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Microcomputing, October 1979 221

kb microcomputing book nook

• HOBBY COMPUTERS ARE HERE!— BK7322— If you want to
come up to speed on how computers work . . . hardware and soft-
ware . . . this is an excellent book. It starts with the fundamentals
and explains the circuits, the basics of programming, along with a
couple of TVT construction projects, ASCII-Baudot, etc. This book
has the highest recommendations as a teaching aid for
newcomers. $4.95.*

• THE NEW HOBBY COMPUTERS-BK7340-This book takes it
from where Hobby Computers Are Here! leaves off, with chapters
on Large Scale Integration, how to choose a microprocessor chip,
an introduction to programming, low cost I/O for a computer, com-
puter arithmetic, checking memory boards, a Baudot monitor/edi-
tor system, an audible logic probe for finding those tough prob-
lems, a ham’s computer, a computer QSO machine . . . and much,
much more! $4.95*

• INTRODUCTION TO MICROPROCESSORS-BK1032-by

Charles Rockwell of MICROLOG, is an ideal reference for the indi-
vidual desiring to understand the hardware aspects of micropro-
cessor systems. Describes the hardware details of computer de-
vices in terms the beginner can understand, instead of treating the
micro chip as a “black box.” Specific systems are not described
and programming is only briefly discussed. $17.50 U.S. and
Canada; $20 elsewhere.*

• BASIC NEW 2ND EDITION— BK1081— by Bob Albrecht. Self-teaching guide to the computer language you will need to know
for use with your microcomputer. This is one of the easiest ways to learn computer programming. $5.95.*

• SCIENTIFIC RESEARCH INSTRUMENT’S BASIC SOFTWARE LIBRARY is a complete do-it-yourself kit, written in every-
body’s BASIC, immediately executable in ANY computer with 8K; no other peripherals needed. Volume I contains business and
recreational programs and is 300 pages. Volume II is 260 pages and contains math, engineering, statistics and plotting pro-
grams. Volume III contains money managing, advanced business programs such as billing, A/R, inventory, payroll, etc. Volume
IV contains general purpose programs such as loans, rates, retirement, plus games: Poker, Enterprise (take charge while Capt.
Kirk is away), Football and more! Volume V is filled with experimenters’ programs, including games, pictures and misc. prob-
lems such as “logic.” Volume I — LB1002— & Volume II— LB1003— $24.95* each, Volume III — LB1004— $39.95*, Volume IV—
LB1005 — & Volume V— LB1006— $9.95* each.

• MICROPROCESSOR INTERFACING TECHNIQUES— BK1037— by Austin Lesea & Rodnay Zaks will teach you how to inter-
connect a complete system and interface it to all the usual peripherals. It covers hardware and software skills and techniques,
including the use and design of model buses such as the IEEE 488 or S100. $13.95.*

WHAT TO DO
AFTER you HIT
RETURN

P.C.C's First Book of
Computer Games

• TTL COOKBOOK— BK1063— by Donald Lancaster. Explains
what TTL is, how it works, and how to use it. Discusses practical
applications, such as a digital counter and display system, events
counter, electronic stopwatch, digital voltmeter and a digital tach-
ometer. $8.95.

• CMOS COOKBOOK— BK1011— by Don Lancaster. Details the
application of CMOS, the low power logic family suitable for most
applications presently dominated by TTL. Required reading for
every serious digital experimenter! $9.95.*

• TVT COOKBOOK— BK1064— by Don Lancaster. Describes the
use of a standard television receiver as a microprocessor CRT ter-
minal. Explains and describes character generation, cursor con-
trol and interface information in typical, easy-to-understand Lan-
caster style. $9.95.*

• THE “COMPULATOR” BOOK-BUILDING SUPER
CALCULATORS & MINICOMPUTER HARDWARE WITH
CALCULATOR CHIPS-BK1012-by R.P. Haviland, provides
ideas, design info and/or printed circuit boards for calculator chip
projects such as tape control of calculator electronic lock, dial-a-
telephone, etc. $7.95.*

• BASIC COMPUTER GAMES— BK1074— Okay, so once you get your computer and are running in BASIC, then what? Then you
need some programs in BASIC, that’s what. This book has 101 games for you from very simple to real buggers. You get the
games, a description of the games, the listing to put in your computer and a sample run to show you how they work. Fun. Any
one game will be worth more than the price of the book for the fun you and your family will have with it. $7.50.*

• WHAT TO DO AFTER YOU HIT RETURN— BK1071 — PCC’s first book of computer games ... 48 different computer games
you can play in BASIC . . . programs, descriptions, many illustrations. Lunar Landing, Hammurabi, King, Civel 2, Qubic 5, Tax-
man, Star Trek, Crash, Market, etc. $10.95.*

• MICROCOMPUTING CODING SHEETS Microcomputing's dozen or so programmers wouldn’t try to work without these
handy scratch pads, which help prevent the little errors that can cost hours and hours of programming time. Available for pro-
gramming is Assembly/Machine Language (PD1001), which has columns for address, instruction (3 bytes), source code (label,
op code, operand) and comments; and for BASIC (PD1002) which is 72 columns wide. 50 sheets to a pad. $2.39.*

*Use the order card in the back of this magazine or itemize your order on a separate piece of paper and mail to:

Kilobaud Microcomputing Book Department • Peterborough NH 03458. Be sure to include check or detailed credit card information.

All orders, add $1.00 handling.

FOR TOLL FREE ORDERING CALL 1-800-258-5473

kb microcomputing book nook

• PROGRAMMING IN PASCAL— BK1 140— by Peter Grogono. The
computer programming language PASCAL was the first language
to embody in a coherent way the concepts of structured program-
ming, which has been defined by Edsger Dijkstra and C.A.R.

Hoare. As such, it is a landmark in the development of program-
ming languages. PASCAL was developed by Niklaus Wirth in
Zurich; it is derived from the language ALGOL 60 but is more
powerful and easier to use. PASCAL is now widely accepted as a
useful language that can be efficiently implemented, and as an ex-
cellent teaching tool. It does not assume knowledge of any other
programming language; it is therefore suitable for an introductory
course. $9.95/

• MICROPROCESSOR LEXICON-ACRONYMS AND DEFINI-
TIONS— BK1040— compiled by the staff of SYBEX, is a convenient
reference in pocket-size format. Sections include acronyms and
definitions, part numbers and their definitions, S-100 signals;

RS232 signals, IEEE 499 signals, microcomputers and micropro-
cessors, JETDS summary (military) and a code conversion table.

$2.95/

• INSTANT BASIC— BK1 127— by Jerald R. Brown. For the per-
sonal computer enthusiast or the user of DEC’S BASIC PLUS lan-
guage, here is a new book to teach you BASIC. It teaches BASIC to
beginners using interesting programming ideas and applications
that will be easily understood by the home computer programmer.

BASIC PLUS users know that the two languages are very similar,
so this book can be used by them as well. This is an “active par-
ticipation” workbook, designed to be used with your home com-
puter so you can learn by doing! Ideas are slowly introduced in a
nonmathematical context so the beginner can quickly learn good
programming techniques. $6.00/

• MY COMPUTER LIKES ME ... WHEN I SPEAK BASIC— BK1039— An introduction to BASIC . . . simple enough for kids. If you
want to teach BASIC to anyone quickly, this is the way to go. $2.00/

• COMPUTER PROGRAMMING HANDBOOK— BK1014— by Peter Stark. A complete guide to computer programming and data
processing. Includes many worked-out examples and history of computers. $9.95/

• MICROCOMPUTER DICTIONARY— BK1034— This microcomputer dictionary fills the need to become quickly acquainted
with the terminology and nomenclature of the revolution in computers. There is also a comprehensive electronics/computer
abbreviations and acronyms section. $15.95/

• YOUR HOME COMPUTER— BK1 172 — by James White, is an in-
troduction to the world of personal microcomputing. This book
tells you everything you want to know about home computing and
gives the computer novice a painless introduction to microcom-
puter technology and terminology, beginning with what com-
puters are and how they work. This basic book requires no prior
knowledge or experience in electronics or computing. It provides
information about home computer kits; guidelines for selecting
and building your own microcomputer, how to use your home com-
puter and what you can do with it; lists of computer stores, clubs,
periodicals; and answers to many more of your questions about
microcomputers and the jargon surrounding the personal comput-
ing scene today. $6.00/

• HOW TO BUILD A MICROCOMPUTER-AND REALLY UNDER-
STAND IT— BK7325— by Sam Creason. The electronics hobbyist
who wants to build his own microcomputer system now has a prac-
tical “How-To” guidebook. This book is a combination technical
manual and programming guide that takes the hobbyist step-by-
step through the design, construction, testing and debugging of a
complete microcomputer system. Must reading for anyone desir-
ing a true understanding of small computer systems. $9.95/

THE BASIC HANDBOOK— BK1 174— by David Lien. This book is
unique, it is a virtual ENCYCLOPEDIA of BASIC. While not favoring
one computer over another, it explains over 250 BASIC words, how
to use them and alternate strategies. If a computer does not
possess the capabilities of a needed or specified word, there are
often ways to accomplish the same function by using another
word or combination of words. That’s where the HANDBOOK
comes in. It helps you get the most from your computer, be it a
“bottom-of-the-line” micro or an oversized monster. $14.95/

• SCELBI’S FIRST BOOK OF COMPUTER GAMES— BK1048— Need a game for your 8008 or 8080 microprocessor? This book
has three popular games: “Space Capture,” “Hexpawn” and “Hangman.” Complete flowcharts, logic description, program
listing and instructions are provided. A must for the game freak! $14.95/

• MICROCOMPUTER PRIMER— BK1035— by M. Waite and M. Pardee. Describes basic computer theory, explains numbering
systems and introduces the reader to the world of programming. Describes the world of microcomputing in “real world” termi-
nology. $7.95/

• THE STORY OF COMPUTERS— BK1056— by Donald D. Spencer, is to computer books what Dick and Jane is to novels . . .
elementary, gives the non-computerist a fair idea of what the hobbyist is talking about when he speaks computer lingo. At-
tempts to explain what computers are and can do to a spouse, child or any non-electronics-minded friend. $4.95/

*Use the order card in the back of this magazine or itemize your order on a separate piece of paper and mail to:

Kilobaud Microcomputing Book Department • Peterborough NH 03458. Be sure to include check or detailed credit card information.

All orders, add $1.00 hananng.

FOR CUSTOMER SERVICE CALL 603-924-7298

kb microcomputing bookj\

PIMS

Personal Information
Management System

• PROGRAMMING THE 6502-BK1005— Rodnay Zaks has de-
signed a self-contained text to learn programming, using the
6502. It can be used by a person who has never programmed
before, and should be of value to anyone using the 6502. The
many exercises will allow you to test yourself and practice the
concepts presented. $10.95*

• 6502 APPLICATIONS BOOK— BK1006— Rodnay Zaks pre-
sents practical-application techniques for the 6502
microprocessor, assuming an elementary knowledge of micro-
processor programming. You will build and design your own
domestic-use systems and peripherals. Self-test exercises in-
cluded. $12.95*

• HOW TO SELL ANYTHING TO ANYBODY— BK7306— According to The Guiness Book of World Records , the author, Joe Girard,
is “the world’s greatest salesman.” This book reveals how he made a fortune— and how you can, too. $2.25.*

• PIMS: PERSONAL INFORMATION MANAGEMENT SYSTEM— BK1009— Learn how to unleash the power of a personal com-
puter for your own benefit in this ready-to-use data-base management program. $9.95.*

• SIXTY CHALLENGING PROBLEMS WITH BASIC SOLUTIONS (2nd Edition)— BK1073— by Donald Spencer, provides the serious
student of BASIC programming with interesting problems and solutions. No knowledge of math above algebra required. Includes a
number of game programs, as well as programs for financial interest, conversions and numeric manipulations. $6.95.*

• 8080 SOFTWARE GOURMET GUIDE AND COOKBOOK—

BK1102 — If you have been spending too much time developing
simple routines for your 8080, try this new book by Scelbi Com-
puting and Robert Findley. Desribes sorting, searching, and
many other routines for the 8080 user. $9.95.*

• 6800 SOFTWARE GOURMET GUIDE AND COOKBOOK—
BK1075— Like its culinary cousin, The 8080 Gourmet Guide, this
new book by Scelbi Computing and Robert Findley describes
sorting, searching and other routines— this time for the 6800
user. $10.95.*

• LOW-COST, PERSONAL COMPUTER-BASED INVESTMENT
DECISION SYSTEMS — BK1 101 — Use this guidebook by Man-
Computer Systems, Inc.’s president, Jerry Felsen, to develop in-
expensive personal computer systems that can help you make
better investment decisions. $8.95.*

• HOW TO MAKE MONEY WITH COMPUTERS-BK1003-ln 10

information-packed chapters, this original book describes more
than 30 computer-related, money-making, high profit, low capital
investment opportunities. $15.00.*

• ADD ’N STAC— BX1003— If you’ve got programs lying around
and want them organized in easy-to-locate fashion Add ’N Stac is
the answer. Each unit stores eight cassettes. Each module locks
together with the next and grows with your collection. Build
yourself a software library with Add ’N Stac by ordering from the
Book Nook. As your library grows you’ll need more of these
handy units so order more than one today. Several colors are
available and you can mount them to your wall, desk, table or
keep them loose for taking with you. Colors and prices are:

Smoke $3.00*; Black, Dark Blue, Orange, Brown, White, Red
$2.50.*

*Use the order card in the back of this magazine or itemize your order on a separate piece of paper and mail to:

Kilobaud Microcomputing Book Department • Peterborough NH 03458. Be sure to include check or detailed credit card information.

All orders, add $1.00 handling.

224 Microcomputing, October 1979

kb microcomputing book nook

• AN INTRODUCTION TO MICROCOM-
PUTERS, VOL. 0— BK1130— The Begin-
ner’s Book— Written for readers who know
nothing about computers— for those who
have an interest in how to use computers
—and for everyone else who must live with
computers and should know a little about
them. The first in a series of 4 volumes, this
book will explain how computers work and
what they can do. Computers have be-
come an integral part of life and society.
During any given day you are affected by
computers, so start learning more about
them with Volume 0. $7.95.*

• VOL. I — BK1030 — Dedicated to the
basic concepts of microcomputers and
hardware theory. The purpose of Volume I
is to give you a thorough understanding of
what microcomputers are. From basic
concepts (which are covered in detail),
Volume I builds the necessary compo-
nents of a microcomputer system. This
book highlights the difference between
minicomputers and microcomputers.
$9.50.*

• VOL. II— BK1031 (loose leaf)— $25.00*;
BK1040 (with binder)— $30.00*— Contains
descriptions of individual microproces-
sors and support devices used only with
the parent microprocessor. Volume
describes all available chips.

• VOL. Ill — BK1132 (loose leaf)— $15.00*;
BK1133 (with binder)— $20.00.* Contains
descriptions of all support devices that
can be used with any microprocessor.

• FUN WITH COMPUTERS AND BASIC—
BK1021 — by Donald D. Spencer, contains
an easy-to-understand explanation of the
BASIC Programming Language and is in-
tended for persons who have had no pre-
vious exposure to computer programming.
Over half the book is devoted to problems
using games, puzzles, and mathematical
recreations. A superior book for self-
teaching and learning computer program-
ming. $6.95.*

• ADVANCED BASIC-BK1000— Applica-
tions and problems by James Coan is for
those who want to extend their expertise
with BASIC. Offers advanced techniques
and applications. $7.95.*

• PAYROLL WITH COST ACCOUNTING-
IN BASIC — BK1001 — by L. Poole & M.
Borchers, includes program listings with
remarks, descriptions, discussions of the
principle behind each program, file
layouts, and a complete user’s manual
with step-by-step instructions, flowcharts,
and simple reports and CRT displays.
Payroll and cost accounting features in-
clude separate payrolls for up to 10 com-
panies, time-tested interactive data entry,
easy correction of data entry errors, job
costing (labor distribution), check printing
with full deduction and pay detail, and 16
different printed reports, including W-2
and 941. $12.50.*

• SOME COMMON BASIC PROGRAMS-

BK1053— published by Adam Osborne &
Associates, Inc. Perfect for non-technical
computerists requiring ready-to-use pro-
grams. Business programs, plus miscel-
laneous programs. Invaluable for the user
who is not an experienced programmer. All
will operate in the stand-alone mode. $9.50
paperback.*

• THE SECRET GUIDE TO COMPUTERS

Parts 1, 2 and 3 by Russ Walter. Part One
describes computers in general, and after
reading for ten minutes you will be writing
simple BASIC programs! Part Two dis-
cusses computer applications. It’s one
thing to master the syntax of the language
such as BASIC and another to solve prob-
lems using the new tool. Part Three
describes programming languages. Ever
heard of APL and QLISP? BASIC is not the
only language used to program comput-
ers. 7th Edition. Part I — BK1050— $2.75*;
Part II — BK1051— $2.50*; Part III — BK1052
—$3.50.*

‘Use the order card in the back of this magazine or itemize your order on a separate piece of paper and mail to:

Kilobaud Microcomputing Book Department • Peterborough NH 03458. Be sure to include check or detailed credit card information.

All orders, add $1.00 handling.

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Microcomputing, October 1979 225

kilobaud

MICROCOMPUTING ” LIST OF 4DMERTISERS

A90 Aardvark Technical Services. . 178

A88 AB Computers 192

A75 ACS Service 17

A38 Advanced Computer Products

217

A102 Adventure International 171

A101 Alpha Byte Storage 171

A66 American Square Computers. . . 66

A103 APF Electronics, Inc 21

A22 AP Products 19

A28 Apple Computer Company 21

A98 Bill Archbold 155

A108 Aries Computer Software, Inc

168

A89 August Automation 164

A71 Automated Simulations. . 181, 190

fe50 Bluebird’s Inc 81

B33 The Bottom Shelf, Inc 43

B43 Buss 180

C128 Cecdat, Inc 174

C151 Chafitz, Inc 23

Cl 22 CompuCover 54

C109 CompuSoft Publishing 87

C64 Computer Corner of NJ 186

Cl 46 The Computer Exchange 155

The Computer Factory 187

C111 Computer Forum 193

C104 Computer Information Exchange

152

C80 Computer Port 149

C153 Computer Simulations Canada

179

C94 The Computerist 188

C81 Computers One 189

C86 Computrex 189

Cl 14 Computronics 93

Cl 24 Cost Effective Computer Services

164

Cl 08 The CPU Shop 103

Cl 45 Cursor Magazine 54

C132 Custom Electronics 59

Cl 29 Cybernetics, Inc 181

D43 Dr. Daley 83

D50 Data/Print 101

D40 Datasearch 192

D59 Davilyn Corp 66

D61 Delta Systems 168

D28 Deltroniks 1$5

* Digital Dynamics, Inc 145

* Digital Research Corp 208

Digital Research Parts 183

D60 Digital Video Systems 218

D48 Disks, Etc 193

E34 Ecosoft 189

* Charles Egetter 163

E37 80-US Journal 187

E36 Electronic Specialists, Inc.

26, 59

E21 Electronic Systems 206, 207

E30 Esmark 107

E48 Exatron 15

E44 Exidy Data Products 22

F21 Falcon Publishing 164

F18 Fuller Electronics 218

F20 Fuller Software 171

G28 Gimix, Inc 113,143,178

G4 Godbout Electronics 201

H46 Hardware-80 218

H20 D.C. Hayes Assoc., Inc 22

H25 Hobby World 194, 195

H45 Houston Micro-Computer Tech.,

Inc 169

124 Innovative Technology 155

132 Instant Software 29, 70, 71

113

Integrand

145

Integrated Circuits Unlimited

200

Intersystems, Inc

..97

121

Intertec Data Systems

3, 47

Jade Computer Products

210,

211

Jameco Electronics 202, 203

J14

Joe Computer

..59

J12

JPC Products

.185

K14

Key Electronics

.218

Kilobaud 67-69

Dr. Lee

. 179

L20

Leedex Corp

.174

L19

Level IV Products, Inc

. 148

L16

Lifeboat Associates

. 165

L25

The Logic Store 54, 152

M77

Madhatter Software

.135

M88

The Mail Mart

.191

Man-Computer Systems, Inc. .

. 118

M17

Marketline, Inc

.133

Ml 07

McClain & Associates, Inc

..54

M113

Mercer Systems

..81

M103

Micro Applications Group —

.130

M89

Micro Architect

,152

Mill

Micro Computer Industries. . .

.192

M110

MicroDaSys

M112

Micro-Innovations

171

M82

Microcomputer Tech., Inc./

Apparat, Inc

, 196

M116

Micro Discount Service

, 178

M73

Micromail

182

M95

Micro Management Systems. .

, 163

M105

Micro Matrix

,171

M54

Micro-Mega

. 96

M115

Micron

152

M81

Micro Products Unltd

178

M67

Microsette Co 26, 54

M44

Micro Technology Unltd

..19

M31

Micro Works

..39

M94

Mid East Micro

191

Ml 06

Midwest Computer Peripherals

168

M70

Midwest Scientific

CIV

M39

Mikos

212

Ml 14

Miller Microcomputer Services

178

Mini Micro Mart

209

M20

Motorola, Inc

.77

M32

Mullen Computer Boards

147

M83

Multi Business Computer Systems

180

M87

Mumford Micro Systems

188

National Radio Institute

.61

N26

N.B. Industries

184

N15

Netronics R & D Ltd.

143, 178,

179

Newman Computer Exchange

23,

205

N24

Northeast Expositions

153

Ohio Scientific 10-13, 119

016

Oklahoma Computer Co

165

OK Machine &Tool

169

On-Line

175

OIO

Optimal Technology, Inc

193

Orthon Computers

.59

Osborne & Associates

161

Otto Electronics

174

P66

Pacific Exchanges

.59

PAIA

184

Percom Data Company, Inc. . .

. CM

P62

Percom Data Company, Inc. . .

.22

P64

Percom Data Company, Inc. . .

.21

P67-73 Percom Data Co., Inc 24,25

P52

The Peripheral People — 109, 190

Personal Computing 79

204

P39

Personal Software

. .4

P60

Practical Applications

164

P21

Priority One 214-216

P65

The Program Store

185

P48

Programma International, Inc.

.38

Q10

Q-Kit

186

Quant Systems

152

Quasar Data Products

184

Quest Electronics

197

R24

Racet Computes

181

Radio Shack

.63

R34

Radio Shack Authorized Sales

Center

188

Rainbow Computing, Inc

186

Ramsey Electronics

157

R32

REAL-LIFE Simulations

178

R33

Realty Software Company

179

Recreational Programmer —

.51

R20

RNB Enterprises 198, 199

Rondure Company

146

SI 06

Sara Tech Electronics, Inc

130

Scelbi Publications

137

S96

Selectronics

219

S101

Semiconductor Surplus

183

S115

Silver Spur Electric Comm. Co.

118

S113

Sirius Systems

185

S74

68 Micro Journal

175

S105

6502 Users Notes

.66

S92

Small Business Applications

168

Sill

Small Systems Services

180

S51

Small Systems Software

182

S46

Smoke Signal Broadcasting. . .

.23

S112

Software Dynamics

.33

S114

The Software Farm

163

S108

Solid State Music

.26

S61

Supersoft

218

S42

Sybex, Inc

127

T70

Talos Systems, Inc

.22

T37

Tano Corp

.55

T57

Taranto & Associates

131

Til

Tarbell Electronics 165, 193

T68

Tecmar, Inc

.26

T26

Telecommunications Services

218

T28

Thinker Toys

123

T56

TNW Corp

218

Tora Systems Limited

175

T41

Total Information Services, Inc.

59,

187

T46

Transition Enterprises, Inc

.54

T69

TYC Software

171

U11

Ucatan Corp

218

U12

Ultimate Computer Systems. .

152

V26

Votrax

. 22

V19

VR Data Corporation

156

Wallen Electronics

213

W22

Wameco, Inc

212

W13

Wasatch Semiconductor Products

188

W20

WEB Associates 26, 53

W25

Western Digital

.76

W21

Western I/O

125

W29

West Side Electronics

189

W16

World Wide Electronics

218

Xitex Corp

126

Young’s

118

From

Kilobaud 115, 192, 220-226

•Reader Service inquiries not honored. Please contact
advertiser directly.

226 Microcomputing, October 1979

■r^Ti

£ 7 §1 \ 1 1 lis

mmm

■ i •

i s * BBSSSM : . !

■e&refl jyp : j

Wi & ul

S-100 Compatibility. 6809 Computability.

IK RAM

10K PROM space

MONBUG II monitor included

2400 baud cassette interface

20 I/O lines

RS-232 level shifters

Real time clock

DMA

Parallel keyboard input
Memory-mapped video firmware

Fully S-100 compatible
(including 8080 type I/O)

A complete system, ready to use.

MD-690 b Single Board Computer
$239 Kit $299 Assembled

^ 6802 Also available - #

Deduct $40.00 miOZl V

6809

16 bit internal arithmetic
Hardware multiplication
Two stack pointers
Two index registers
18 addressing modes
Fully relocatable code
Five interrupts
Up to three times the
throughput of a 4MHz Z-80

MicroDaSys

(213) 9354555

P.O. BOX 36051 , LOS ANGELES, CA 90036, USA

Inventory Problems?

Are you hoving trouble keeping the right nuts
ond bolts in stock? Since even o simple mistake con
cost you time and money, a good inventory system
should do more than just count parts. It should tell
you exactly what you need, when you need it,
where to get it, and how much it will cost.

The MSI Inventory System Seven enables you to
maintain a versatile data base for controlling
inventory. It lists port number, description, quantity
on hand, vendor, cost, selling price, optional
pricing, usage levels for previous month, present
month, and year-to-date, and much more.

When quantity on hand items reach minimum
levels, the System Seven compiles on automatic
reorder list. This list con be generated by spe-
cific vendor os well os a complete listing of
oil materials to be ordered.

In addition to the item listing, the In-
ventory System Seven "bill of materials"
provides you with a complete inventory
of items used in the manufacture of subassemblies
and complete products. It also contains other cost
items such os labor costs, total raw materials costs,
and miscellaneous costs.

The MSI Inventory System Seven is built around
the versatile MSI 6800A Computer with 56K of
RAM. An integral dual mini-floppy memory gives
you on additional 630K of memory and makes

inventory control fast and efficient. The System
Seven will interface with any industry standard CRT,
and you have the option of both a "daisy wheel"
word processor for high quality document prepa-
ration and a dot matrix printer for high speed
production.

The System Seven can be expanded to handle
all your data processing needs or you can select
one of nine other MSI systems now available
for business, industrial, scientific, educational, and
personal applications.

If you need more than just a nuts and bolts
inventory system, we have more informa-
tion about how the Inventory
System Seven can solve your pro
blems economically.

MSI Inventory System Seven

midwest Scientific

220 W. Cedar, Olathe, Kansas 66061,(913)764-3273
TWX 91 0 749 6403 (MSI OLAT), TELEX 42525 (MSI A OLAT)

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